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>

mount/temp.go

@@ -18,7 +18,6 @@ package mount
 
 import (
 	"context"
-	"io/ioutil"
 	"os"
 
 	"github.com/containerd/containerd/log"
@@ -31,7 +30,7 @@ var tempMountLocation = getTempDir()
 // The mounts are valid during the call to the f.
 // Finally we will unmount and remove the temp dir regardless of the result of f.
 func WithTempMount(ctx context.Context, mounts []Mount, f func(root string) error) (err error) {
-	root, uerr := ioutil.TempDir(tempMountLocation, "containerd-mount")
+	root, uerr := os.MkdirTemp(tempMountLocation, "containerd-mount")
 	if uerr != nil {
 		return errors.Wrapf(uerr, "failed to create temp dir")
 	}