Drop py35 jobs
Drop py35 jobs

Python 3.5 was the target runtime for the Rocky release. The current
target py3 runtime for Stein is Python 3.6, so there is no reason to
keep testing against the older version.

https://governance.openstack.org/tc/reference/runtimes/stein.html#python-runtime-for-stein

Change-Id: I094f862ecdc6a8b54168bc4ba6ef857b43dd7f42
Signed-off-by: Sean McGinnis <961eeb09b6d45516665e15b82e013282c4faf575@gmail.com>

openstack/python-brick-cinderclient-ext,openstack/python-brick-cinderclient-ext