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: Ie52d284f270891d09bb09a7ada1e8abdf89bcfcb

ChameleonCloud/python-blazarclient,stackforge/python-blazarclient,openstack/python-blazarclient