diff --git a/go.mod b/go.mod
index b39a23800..dc476abc2 100644
--- a/go.mod
+++ b/go.mod
@@ -163,4 +163,4 @@ require (
 
 toolchain go1.21.0
 
-go 1.20
+go 1.21
diff --git a/tpl/internal/go_templates/htmltemplate/clone_test.go b/tpl/internal/go_templates/htmltemplate/clone_test.go
index 7db335b5b..e42177a6b 100644
--- a/tpl/internal/go_templates/htmltemplate/clone_test.go
+++ b/tpl/internal/go_templates/htmltemplate/clone_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
diff --git a/tpl/internal/go_templates/htmltemplate/content_test.go b/tpl/internal/go_templates/htmltemplate/content_test.go
index fac4774cc..e886ee8ff 100644
--- a/tpl/internal/go_templates/htmltemplate/content_test.go
+++ b/tpl/internal/go_templates/htmltemplate/content_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
@@ -428,7 +428,7 @@ func TestStringer(t *testing.T) {
 	if err := tmpl.Execute(b, s); err != nil {
 		t.Fatal(err)
 	}
-	var expect = "string=3"
+	expect := "string=3"
 	if b.String() != expect {
 		t.Errorf("expected %q got %q", expect, b.String())
 	}
diff --git a/tpl/internal/go_templates/htmltemplate/css_test.go b/tpl/internal/go_templates/htmltemplate/css_test.go
index f44568930..f2b2add3a 100644
--- a/tpl/internal/go_templates/htmltemplate/css_test.go
+++ b/tpl/internal/go_templates/htmltemplate/css_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
diff --git a/tpl/internal/go_templates/htmltemplate/escape_test.go b/tpl/internal/go_templates/htmltemplate/escape_test.go
index b202afde0..66bf50203 100644
--- a/tpl/internal/go_templates/htmltemplate/escape_test.go
+++ b/tpl/internal/go_templates/htmltemplate/escape_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
@@ -944,7 +944,6 @@ func TestEscapeSet(t *testing.T) {
 			t.Errorf("want\n\t%q\ngot\n\t%q", test.want, got)
 		}
 	}
-
 }
 
 func TestErrors(t *testing.T) {
@@ -1194,7 +1193,6 @@ func TestErrors(t *testing.T) {
 		// Check that we get the same error if we call Execute again.
 		if err := tmpl.Execute(buf, nil); err == nil || err.Error() != got {
 			t.Errorf("input=%q: unexpected error on second call %q", test.input, err)
-
 		}
 	}
 }
diff --git a/tpl/internal/go_templates/htmltemplate/example_test.go b/tpl/internal/go_templates/htmltemplate/example_test.go
index 6485c7cfb..de81132c2 100644
--- a/tpl/internal/go_templates/htmltemplate/example_test.go
+++ b/tpl/internal/go_templates/htmltemplate/example_test.go
@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13
-// +build go1.13
-
 package template_test
 
 import (
@@ -83,7 +80,6 @@ func Example() {
 	// 		<div><strong>no rows</strong></div>
 	// 	</body>
 	// </html>
-
 }
 
 func Example_autoescaping() {
@@ -124,7 +120,6 @@ func Example_escape() {
 	// \"Fran \u0026 Freddie\'s Diner\" \u003Ctasty@example.com\u003E
 	// \"Fran \u0026 Freddie\'s Diner\"32\u003Ctasty@example.com\u003E
 	// %22Fran+%26+Freddie%27s+Diner%2232%3Ctasty%40example.com%3E
-
 }
 
 func ExampleTemplate_Delims() {
diff --git a/tpl/internal/go_templates/htmltemplate/exec_test.go b/tpl/internal/go_templates/htmltemplate/exec_test.go
index e91aeafa1..428cddc0d 100644
--- a/tpl/internal/go_templates/htmltemplate/exec_test.go
+++ b/tpl/internal/go_templates/htmltemplate/exec_test.go
@@ -4,8 +4,8 @@
 
 // Tests for template execution, copied from text/template.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
diff --git a/tpl/internal/go_templates/htmltemplate/html_test.go b/tpl/internal/go_templates/htmltemplate/html_test.go
index 2809ee1e2..bea668ef9 100644
--- a/tpl/internal/go_templates/htmltemplate/html_test.go
+++ b/tpl/internal/go_templates/htmltemplate/html_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
diff --git a/tpl/internal/go_templates/htmltemplate/js_test.go b/tpl/internal/go_templates/htmltemplate/js_test.go
index c78f43b5f..61a601b02 100644
--- a/tpl/internal/go_templates/htmltemplate/js_test.go
+++ b/tpl/internal/go_templates/htmltemplate/js_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
@@ -221,7 +221,8 @@ func TestJSStrEscaper(t *testing.T) {
 		{"<!--", `\u003c!--`},
 		{"-->", `--\u003e`},
 		// From https://code.google.com/p/doctype/wiki/ArticleUtf7
-		{"+ADw-script+AD4-alert(1)+ADw-/script+AD4-",
+		{
+			"+ADw-script+AD4-alert(1)+ADw-/script+AD4-",
 			`\u002bADw-script\u002bAD4-alert(1)\u002bADw-\/script\u002bAD4-`,
 		},
 		// Invalid UTF-8 sequence
diff --git a/tpl/internal/go_templates/htmltemplate/multi_test.go b/tpl/internal/go_templates/htmltemplate/multi_test.go
index f3e629b88..c320c4353 100644
--- a/tpl/internal/go_templates/htmltemplate/multi_test.go
+++ b/tpl/internal/go_templates/htmltemplate/multi_test.go
@@ -4,8 +4,8 @@
 
 // Tests for multiple-template execution, copied from text/template.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
@@ -268,7 +268,7 @@ func TestIssue19294(t *testing.T) {
 	// by the contents of "stylesheet", but if the internal map associating
 	// names with templates is built in the wrong order, the empty block
 	// looks non-empty and this doesn't happen.
-	var inlined = map[string]string{
+	inlined := map[string]string{
 		"stylesheet": `{{define "stylesheet"}}stylesheet{{end}}`,
 		"xhtml":      `{{block "stylesheet" .}}{{end}}`,
 	}
diff --git a/tpl/internal/go_templates/htmltemplate/template_test.go b/tpl/internal/go_templates/htmltemplate/template_test.go
index 0838308a1..3a0f7463e 100644
--- a/tpl/internal/go_templates/htmltemplate/template_test.go
+++ b/tpl/internal/go_templates/htmltemplate/template_test.go
@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13
-// +build go1.13
-
 package template_test
 
 import (
@@ -18,7 +15,6 @@ import (
 )
 
 func TestTemplateClone(t *testing.T) {
-
 	orig := New("name")
 	clone, err := orig.Clone()
 	if err != nil {
diff --git a/tpl/internal/go_templates/htmltemplate/transition_test.go b/tpl/internal/go_templates/htmltemplate/transition_test.go
index 0bd38800f..9eb36558b 100644
--- a/tpl/internal/go_templates/htmltemplate/transition_test.go
+++ b/tpl/internal/go_templates/htmltemplate/transition_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
@@ -43,7 +43,6 @@ func TestFindEndTag(t *testing.T) {
 }
 
 func BenchmarkTemplateSpecialTags(b *testing.B) {
-
 	r := struct {
 		Name, Gift string
 	}{"Aunt Mildred", "bone china tea set"}
diff --git a/tpl/internal/go_templates/htmltemplate/url_test.go b/tpl/internal/go_templates/htmltemplate/url_test.go
index 72c8a4fe9..c7e67c211 100644
--- a/tpl/internal/go_templates/htmltemplate/url_test.go
+++ b/tpl/internal/go_templates/htmltemplate/url_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
diff --git a/tpl/internal/go_templates/texttemplate/multi_test.go b/tpl/internal/go_templates/texttemplate/multi_test.go
index 6e383c131..6358383e4 100644
--- a/tpl/internal/go_templates/texttemplate/multi_test.go
+++ b/tpl/internal/go_templates/texttemplate/multi_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build go1.13 && !windows
-// +build go1.13,!windows
+//go:build !windows
+// +build !windows
 
 package template
 
@@ -11,10 +11,11 @@ package template
 
 import (
 	"fmt"
-	"github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate/parse"
 	"os"
 	"strings"
 	"testing"
+
+	"github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate/parse"
 )
 
 const (
@@ -31,22 +32,32 @@ type multiParseTest struct {
 }
 
 var multiParseTests = []multiParseTest{
-	{"empty", "", noError,
+	{
+		"empty", "", noError,
 		nil,
-		nil},
-	{"one", `{{define "foo"}} FOO {{end}}`, noError,
+		nil,
+	},
+	{
+		"one", `{{define "foo"}} FOO {{end}}`, noError,
 		[]string{"foo"},
-		[]string{" FOO "}},
-	{"two", `{{define "foo"}} FOO {{end}}{{define "bar"}} BAR {{end}}`, noError,
+		[]string{" FOO "},
+	},
+	{
+		"two", `{{define "foo"}} FOO {{end}}{{define "bar"}} BAR {{end}}`, noError,
 		[]string{"foo", "bar"},
-		[]string{" FOO ", " BAR "}},
+		[]string{" FOO ", " BAR "},
+	},
 	// errors
-	{"missing end", `{{define "foo"}} FOO `, hasError,
+	{
+		"missing end", `{{define "foo"}} FOO `, hasError,
 		nil,
-		nil},
-	{"malformed name", `{{define "foo}} FOO `, hasError,
 		nil,
-		nil},
+	},
+	{
+		"malformed name", `{{define "foo}} FOO `, hasError,
+		nil,
+		nil,
+	},
 }
 
 func TestMultiParse(t *testing.T) {
@@ -432,7 +443,7 @@ func TestIssue19294(t *testing.T) {
 	// by the contents of "stylesheet", but if the internal map associating
 	// names with templates is built in the wrong order, the empty block
 	// looks non-empty and this doesn't happen.
-	var inlined = map[string]string{
+	inlined := map[string]string{
 		"stylesheet": `{{define "stylesheet"}}stylesheet{{end}}`,
 		"xhtml":      `{{block "stylesheet" .}}{{end}}`,
 	}