Remove ioutil in kubelet and its tests

Signed-off-by: inosato <si17_21@yahoo.co.jp>

pkg/kubelet/kubelet_pods_test.go

@@ -19,7 +19,6 @@ package kubelet
 import (
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"net"
 	"os"
 	"path/filepath"
@@ -182,11 +181,11 @@ fe00::2	ip6-allrouters
 // writeHostsFile will write a hosts file into a temporary dir, and return that dir.
 // Caller is responsible for deleting the dir and its contents.
 func writeHostsFile(filename string, cfg string) (string, error) {
-	tmpdir, err := ioutil.TempDir("", "kubelet=kubelet_pods_test.go=")
+	tmpdir, err := os.MkdirTemp("", "kubelet=kubelet_pods_test.go=")
 	if err != nil {
 		return "", err
 	}
-	return tmpdir, ioutil.WriteFile(filepath.Join(tmpdir, filename), []byte(cfg), 0644)
+	return tmpdir, os.WriteFile(filepath.Join(tmpdir, filename), []byte(cfg), 0644)
 }
 
 func TestManagedHostsFileContent(t *testing.T) {