refactor: move from io/ioutil to io and os package

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>

runtime/v2/runc/v2/service.go

@@ -22,7 +22,7 @@ package v2
 import (
 	"context"
 	"encoding/json"
-	"io/ioutil"
+	"io"
 	"os"
 	"path/filepath"
 	"sync"
@@ -245,7 +245,7 @@ func (s *service) StartShim(ctx context.Context, opts shim.StartOpts) (_ string,
 	}()
 	// make sure to wait after start
 	go cmd.Wait()
-	if data, err := ioutil.ReadAll(os.Stdin); err == nil {
+	if data, err := io.ReadAll(os.Stdin); err == nil {
 		if len(data) > 0 {
 			var any ptypes.Any
 			if err := proto.Unmarshal(data, &any); err != nil {