tpl/internal: Sync Go template src to Go 1.20

Updates #10691

tpl/internal/go_templates/htmltemplate/content.go

@@ -51,7 +51,7 @@ var (
 
 // indirectToStringerOrError returns the value, after dereferencing as many times
 // as necessary to reach the base type (or nil) or an implementation of fmt.Stringer
-// or error,
+// or error.
 func indirectToStringerOrError(a any) any {
 	if a == nil {
 		return nil