Add Python 3 Train unit tests

This is a mechanically generated patch to ensure unit testing is in place
for all of the Tested Runtimes for Train.

See the Train python3-updates goal document for details:
https://governance.openstack.org/tc/goals/train/python3-updates.html

Change-Id: Ib3e0b4220d9a8a076ba2c26ac68852aa3953f134
Story: #2005924
Task: #34240
2 files changed