use istio client-go library instead of knative (#1661)

use istio client-go library instead of knative
bump kubernetes dependency version
change code coverage to codecov

vendor/k8s.io/apiserver/pkg/admission/plugin/namespace/lifecycle/admission.go

@@ -17,13 +17,14 @@ limitations under the License.
 package lifecycle
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"time"
 
 	"k8s.io/klog"
 
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
@@ -73,7 +74,7 @@ var _ = initializer.WantsExternalKubeInformerFactory(&Lifecycle{})
 var _ = initializer.WantsExternalKubeClientSet(&Lifecycle{})
 
 // Admit makes an admission decision based on the request attributes
-func (l *Lifecycle) Admit(a admission.Attributes) error {
+func (l *Lifecycle) Admit(ctx context.Context, a admission.Attributes, o admission.ObjectInterfaces) error {
 	// prevent deletion of immortal namespaces
 	if a.GetOperation() == admission.Delete && a.GetKind().GroupKind() == v1.SchemeGroupVersion.WithKind("Namespace").GroupKind() && l.immortalNamespaces.Has(a.GetName()) {
 		return errors.NewForbidden(a.GetResource().GroupResource(), a.GetName(), fmt.Errorf("this namespace may not be deleted"))