Update Certificate and Issuer to v1

Cert-manager 1.7 removes support for prerelease CR versions, which were deprecated in CM 1.4.

This PR updates the `apiVersion` to `v1` with no other changes. I have verified using `cmctl convert` that this results in a valid manifest.

Author: DWSR

config/certmanager/certificate.yaml

@@ -1,16 +1,14 @@
 # The following manifests contain a self-signed issuer CR and a certificate CR.
 # More document can be found at https://docs.cert-manager.io
-# WARNING: Targets CertManager 0.11 check https://docs.cert-manager.io/en/latest/tasks/upgrading/index.html for 
-# breaking changes
-apiVersion: cert-manager.io/v1alpha2
+apiVersion: cert-manager.io/v1
 kind: Issuer
 metadata:
   name: selfsigned-issuer
   namespace: system
 spec:
   selfSigned: {}
 ---
-apiVersion: cert-manager.io/v1alpha2
+apiVersion: cert-manager.io/v1
 kind: Certificate
 metadata:
   name: serving-cert  # this name should match the one appeared in kustomizeconfig.yaml