Make gate-sqlalchemy-migrate-python33 non-voting

Apparently when the py33 job was enabled for migrate
in commit 7ac466af2dc5ae69d62a46bd7e71b0a813761b01 the
job wasn't running yet, but it doesn't work, there are
script tests that fail with python 3.3 so let's make
it non-voting since it's blocking other changes from
getting in and the project doesn't claim support for
python 3.3.

Closes-Bug: #1403965

Change-Id: Iba034445006a3016be496614b217ebaec98b243b
Merge "Make gate-sqlalchemy-migrate-python33 non-voting"