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/log/stack.go

@@ -7,7 +7,7 @@ package log
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"runtime"
 )
 
@@ -38,7 +38,7 @@ func Stack(skip int) string {
 		fmt.Fprintf(buf, "%s:%d (0x%x)\n", filename, lineNumber, programCounter)
 		// Now try to print the offending line
 		if filename != lastFilename {
-			data, err := ioutil.ReadFile(filename)
+			data, err := os.ReadFile(filename)
 			if err != nil {
 				// can't read this sourcefile
 				// likely we don't have the sourcecode available