Remove ioutil from client-go

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

Kubernetes-commit: 88dfa51b6003c90e8f0a0508939a1d79950a40df

util/testing/fake_handler.go

@@ -17,7 +17,7 @@ limitations under the License.
 package testing
 
 import (
-	"io/ioutil"
+	"io"
 	"net/http"
 	"net/url"
 	"reflect"
@@ -83,7 +83,7 @@ func (f *FakeHandler) ServeHTTP(response http.ResponseWriter, request *http.Requ
 	response.WriteHeader(f.StatusCode)
 	response.Write([]byte(f.ResponseBody))
 
-	bodyReceived, err := ioutil.ReadAll(request.Body)
+	bodyReceived, err := io.ReadAll(request.Body)
 	if err != nil && f.T != nil {
 		f.T.Logf("Received read error: %v", err)
 	}

util/testing/fake_openapi_handler.go

@@ -18,8 +18,8 @@ package testing
 
 import (
 	"encoding/json"
+	"io"
 	"io/fs"
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
 	"os"
@@ -71,7 +71,7 @@ func NewFakeOpenAPIV3Server(specsPath string) (*FakeOpenAPIServer, error) {
 		}
 
 		defer file.Close()
-		vals, err := ioutil.ReadAll(file)
+		vals, err := io.ReadAll(file)
 		if err != nil {
 			panic(err)
 		}

util/testing/tmpdir.go

@@ -17,7 +17,6 @@ limitations under the License.
 package testing
 
 import (
-	"io/ioutil"
 	"os"
 )
 
@@ -26,7 +25,7 @@ import (
 // deleted with a call to "os.RemoveAll(...)".
 // In case of error, it'll return an empty string and the error.
 func MkTmpdir(prefix string) (string, error) {
-	tmpDir, err := ioutil.TempDir(os.TempDir(), prefix)
+	tmpDir, err := os.MkdirTemp(os.TempDir(), prefix)
 	if err != nil {
 		return "", err
 	}