Bump k8s.io/kubectl from 0.20.5 to 0.21.2

Bumps [k8s.io/kubectl](https://github.com/kubernetes/kubectl) from 0.20.5 to 0.21.2.
- [Release notes](https://github.com/kubernetes/kubectl/releases)
- [Commits](kubernetes/kubectl@v0.20.5...v0.21.2)

---
updated-dependencies:
- dependency-name: k8s.io/kubectl
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

go.mod

@@ -15,7 +15,6 @@ require (
 	github.com/derailed/popeye v0.9.0
 	github.com/derailed/tview v0.6.1
 	github.com/drone/envsubst v1.0.2 // indirect
-	github.com/emicklei/go-restful v2.15.0+incompatible // indirect
 	github.com/fatih/color v1.10.0
 	github.com/fsnotify/fsnotify v1.4.9
 	github.com/fvbommel/sortorder v1.0.2
@@ -36,12 +35,12 @@ require (
 	golang.org/x/text v0.3.6
 	gopkg.in/yaml.v2 v2.4.0
 	helm.sh/helm/v3 v3.5.3
-	k8s.io/api v0.20.5
-	k8s.io/apimachinery v0.20.5
-	k8s.io/cli-runtime v0.20.5
-	k8s.io/client-go v0.20.5
+	k8s.io/api v0.21.2
+	k8s.io/apimachinery v0.21.2
+	k8s.io/cli-runtime v0.21.2
+	k8s.io/client-go v0.21.2
 	k8s.io/klog/v2 v2.8.0
-	k8s.io/kubectl v0.20.5
-	k8s.io/metrics v0.20.5
+	k8s.io/kubectl v0.21.2
+	k8s.io/metrics v0.21.2
 	sigs.k8s.io/yaml v1.2.0
 )