Fix access to flowcontrol APIs

[FedericoHeichou]

Hello, I have a rbac in my k8s, and the cert-manager-webhook-pdns keeps logging something like: Cannot list resource "prioritylevelconfigurations" and "flowschemas" in API group "flowcontrol.apiserver.k8s.io"

I added in the ClusterRole cert-manager-webhook-pdns

  - apiGroups:
      - 'flowcontrol.apiserver.k8s.io'
    resources:
      - 'flowschemas'
      - 'prioritylevelconfigurations'
    verbs:
      - 'watch'
      - 'list'

And now it works.

PS: I don't know if is ok to edit this file only, I didn't check the full repo

[zachomedia]

Thank you!