Add release notes job template

Without this job template there are no release notes published [1].

[1] https://docs.openstack.org/releasenotes/python-cloudkittyclient

Change-Id: I8ab231a4c563ecc2f8db22bade12bf4afa9fafc8

Author: priteau

.zuul.yaml

@@ -49,6 +49,7 @@
       - openstack-python3-xena-jobs
       - openstackclient-plugin-jobs
       - publish-openstack-docs-pti
+      - release-notes-jobs-python3
     check:
       jobs:
         - cloudkittyclient-devstack-functional-v1-client: