Enable gate/check (with voting) for taskflow-python34

The non-voting check has been running for about a week
now without any problems so I think it's fair to turn
it into a voting check so that the taskflow team continues
to maintain the python34 compatibility on an ongoing basis.

Change-Id: Icc080c6bb5943a69167bc70b12dc2b123097512e
Merge "Enable gate/check (with voting) for taskflow-python34"