Remove test_compat.py from py33 tests

File tests/unit/test_compat.py was removed in commit
I06b90f789ae21f2ef8b8071b4298bfc0406482a6 so we should remove
it from python 3.3 tests list to get test passed.

Related to blueprint make-python3-compatible

Change-Id: I4525a7355de509a823e7fe99ed023b1d2365db11
Merge "Remove test_compat.py from py33 tests"