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/charset/charset.go

@@ -8,7 +8,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"strings"
 	"unicode/utf8"
 
@@ -78,7 +77,7 @@ func ToUTF8WithErr(content []byte) (string, error) {
 
 // ToUTF8WithFallback detects the encoding of content and coverts to UTF-8 if possible
 func ToUTF8WithFallback(content []byte) []byte {
-	bs, _ := ioutil.ReadAll(ToUTF8WithFallbackReader(bytes.NewReader(content)))
+	bs, _ := io.ReadAll(ToUTF8WithFallbackReader(bytes.NewReader(content)))
 	return bs
 }