release: update operator version to v0.13.0

Update operator version from v0.12.0 to v0.13.0.

Signed-off-by: Niteesh Dubey <niteesh@us.ibm.com>

Author: Niteesh Dubey

config/release/kustomization.yaml

@@ -4,4 +4,4 @@ resources:
 # newTag points to the latest release image and must be updated before tagging a new release
 images:
 - name: quay.io/confidential-containers/operator
-  newTag: v0.12.0
+  newTag: v0.13.0