Cleanup test output

[cpnota]

We get some random junk:

python -m unittest discover -s all -p "*test.py" -t .
...................................................A.L.E: Arcade Learning Environment (version 0.8.1+53f58b7)
[Powered by Stella]
........................................./home/cnota/miniconda3/envs/all/lib/python3.9/site-packages/gym/envs/registration.py:14: PkgResourcesDeprecationWarning: Parameters to load are deprecated.  Call .resolve and .require separately.
  result = entry_point.load(False)
pybullet build time: Mar 26 2022 03:01:35
..argv[0]=
argv[0]=
.argv[0]=
argv[0]=
...............................................................................................
----------------------------------------------------------------------
Ran 190 tests in 17.452s

We can at least disable this by mocking sys.out.

[cpnota]

Unfortunately this is very difficult to fix without hacks, because the print statements come from within C code. In the interest of not adding confusing junk to the unit tests that could break output in otherwise, I'm going to close this.