Bump k8s.io/api from 0.20.9 to 0.28.1

Bumps [k8s.io/api](https://github.com/kubernetes/api) from 0.20.9 to 0.28.1.
- [Commits](kubernetes/api@v0.20.9...v0.28.1)

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

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

go.mod

@@ -3,11 +3,12 @@ module github.com/cloudbees/inject-metadata-velero-plugin
 go 1.14
 
 require (
+	github.com/googleapis/gnostic v0.5.5 // indirect
 	github.com/pkg/errors v0.9.1
 	github.com/sirupsen/logrus v1.8.1
 	github.com/vmware-tanzu/velero v1.7.0
-	k8s.io/api v0.20.9
-	k8s.io/apimachinery v0.22.3
+	k8s.io/api v0.28.1
+	k8s.io/apimachinery v0.28.1
 )
 
 replace github.com/gogo/protobuf => github.com/gogo/protobuf v1.3.2