Upgrade to Go 1.23

Fixes #12763

testscripts/commands/mod.txt

@@ -18,7 +18,8 @@ hugo mod clean
 ! stderr .
 stdout 'hugo: removed 1 dirs in module cache for \"github.com/bep/empty-hugo-module\"'
 hugo mod clean --all
-stdout 'Deleted 2\d{2} files from module cache\.'
+# Currently this is 299 on MacOS and 301 on Linux.
+stdout 'Deleted (2|3)\d{2} files from module cache\.'
 cd submod
 hugo mod init testsubmod
 cmpenv go.mod $WORK/golden/go.mod.testsubmod

testscripts/commands/mod_npm.txt

@@ -2,6 +2,7 @@
 
 dostounix golden/package.json
 
+
 hugo mod npm pack
 cmp package.json golden/package.json
 
@@ -41,3 +42,4 @@ path="github.com/gohugoio/hugoTestModule2"
 }
 -- go.mod --
 module github.com/gohugoio/hugoTestModule
+go 1.20

testscripts/commands/mod_npm_withexisting.txt

@@ -55,3 +55,4 @@ path="github.com/gohugoio/hugoTestModule2"
 }
 -- go.mod --
 module github.com/gohugoio/hugoTestModule
+go 1.20