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
Note that openstack-python35-jobs is retained since this charm is supported
on Xenial.
Change-Id: I80a54de2107c44694b5bd062988b67aae3eda1fe
Story: #2005924
Task: #34228
We want to default to running all tox environments under python 3, so
set the basepython value in each environment.
We do not want to specify a minor version number, because we do not
want to have to update the file every time we upgrade python.
We do not want to set the override once in testenv, because that
breaks the more specific versions used in default environments like
py35 and py36.
Change-Id: I59091ad46d42925392ce07329c9c6a301500a5eb
Signed-off-by: Doug Hellmann <doug@doughellmann.com>