Bump k8s.io/api from 0.20.5 to 0.21.0

Bumps [k8s.io/api](https://github.com/kubernetes/api) from 0.20.5 to 0.21.0.
- [Release notes](https://github.com/kubernetes/api/releases)
- [Commits](https://github.com/kubernetes/api/compare/v0.20.5...v0.21.0)

Signed-off-by: dependabot[bot] <support@github.com>

vendor/github.com/google/go-cmp/cmp/export_panic.go

@@ -0,0 +1,15 @@
+// Copyright 2017, The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build purego
+
+package cmp
+
+import "reflect"
+
+const supportExporters = false
+
+func retrieveUnexportedField(reflect.Value, reflect.StructField, bool) reflect.Value {
+	panic("no support for forcibly accessing unexported fields")
+}