Replace deprecated ioutil with io and os

https://pkg.go.dev/io/ioutil is deprecated since Go 1.16.

tpl/data/resources.go

@@ -16,7 +16,7 @@ package data
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/url"
 	"path/filepath"
@@ -62,7 +62,7 @@ func (ns *Namespace) getRemote(cache *filecache.Cache, unmarshal func([]byte) (b
 			}
 
 			var b []byte
-			b, err = ioutil.ReadAll(res.Body)
+			b, err = io.ReadAll(res.Body)
 			if err != nil {
 				return nil, err
 			}

tpl/openapi/openapi3/openapi3.go

@@ -16,7 +16,7 @@ package openapi3
 
 import (
 	"fmt"
-	"io/ioutil"
+	"io"
 
 	gyaml "github.com/ghodss/yaml"
 
@@ -74,7 +74,7 @@ func (ns *Namespace) Unmarshal(r resource.UnmarshableResource) (*OpenAPIDocument
 		}
 		defer reader.Close()
 
-		b, err := ioutil.ReadAll(reader)
+		b, err := io.ReadAll(reader)
 		if err != nil {
 			return nil, err
 		}

tpl/partials/partials.go

@@ -20,7 +20,6 @@ import (
 	"fmt"
 	"html/template"
 	"io"
-	"io/ioutil"
 	"strings"
 	"time"
 
@@ -193,7 +192,7 @@ func (ns *Namespace) include(ctx context.Context, name string, dataList ...any)
 		}
 
 		// We don't care about any template output.
-		w = ioutil.Discard
+		w = io.Discard
 	} else {
 		b := bp.GetBuffer()
 		defer bp.PutBuffer(b)

tpl/transform/unmarshal.go

@@ -15,7 +15,7 @@ package transform
 
 import (
 	"fmt"
-	"io/ioutil"
+	"io"
 	"strings"
 
 	"github.com/gohugoio/hugo/resources/resource"
@@ -83,7 +83,7 @@ func (ns *Namespace) Unmarshal(args ...any) (any, error) {
 			}
 			defer reader.Close()
 
-			b, err := ioutil.ReadAll(reader)
+			b, err := io.ReadAll(reader)
 			if err != nil {
 				return nil, err
 			}