Add Python3 xena unit tests
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: I7db9ad45d719db4912a365043bfea5944bb71dfd

openstack/designate,openstack/designate,openstack/designate