Add Python3 xena unit tests

This is an automatically generated patch to ensure unit testing
is in place for all the of the tested runtimes for xena.

See also the PTI in governance [1].

[1]: https://governance.openstack.org/tc/reference/project-testing-interface.html

Change-Id: Ie0255d5300b303e9392497d6494fdc5f6e08eb53

Author: openstackadmin

.zuul.yaml

@@ -46,7 +46,7 @@
       - openstack-lower-constraints-jobs
       - check-requirements
       - openstack-cover-jobs
-      - openstack-python3-wallaby-jobs
+      - openstack-python3-xena-jobs
       - openstackclient-plugin-jobs
       - publish-openstack-docs-pti
     check: