refactor: move from io/ioutil to io and os package (#17109)

The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.

Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/git/repo_language_stats_nogogit.go

@@ -12,8 +12,8 @@ import (
 	"bytes"
 	"context"
 	"io"
-	"io/ioutil"
 	"math"
+	"os"
 
 	"code.gitea.io/gitea/modules/analyze"
 	"code.gitea.io/gitea/modules/log"
@@ -71,7 +71,7 @@ func (repo *Repository) GetLanguageStats(commitID string) (map[string]int64, err
 		indexFilename, deleteTemporaryFile, err := repo.ReadTreeToTemporaryIndex(commitID)
 		if err == nil {
 			defer deleteTemporaryFile()
-			tmpWorkTree, err := ioutil.TempDir("", "empty-work-dir")
+			tmpWorkTree, err := os.MkdirTemp("", "empty-work-dir")
 			if err == nil {
 				defer func() {
 					_ = util.RemoveAll(tmpWorkTree)