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>

integration/image_load_test.go

@@ -17,7 +17,6 @@
 package integration
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -40,8 +39,8 @@ func TestImageLoad(t *testing.T) {
 	t.Logf("docker save image into tarball")
 	output, err := exec.Command("docker", "pull", testImage).CombinedOutput()
 	require.NoError(t, err, "output: %q", output)
-	// ioutil.TempFile also opens a file, which might prevent us from overwriting that file with docker save.
-	tarDir, err := ioutil.TempDir("", "image-load")
+	// os.CreateTemp also opens a file, which might prevent us from overwriting that file with docker save.
+	tarDir, err := os.MkdirTemp("", "image-load")
 	tar := filepath.Join(tarDir, "image.tar")
 	require.NoError(t, err)
 	defer func() {