This commit simply runs "black" on all our Python files except
those in testsuites/tests/.
Note that I ran into one small difficulty when reformatting setup.py,
where black was reformatting a couple of lines in the code in a way
that it triggered the following E231 flake8 violations:
setup.py:23:69: E231 missing whitespace after ','
setup.py:25:74: E231 missing whitespace after ','
This is a known issue with black...
https://github.com/psf/black/issues/1288
... which is fortunately easily worked around by simply removing
the offending comma (black does not add it back).
Change-Id: I492eb1ca5fa371d063e691f7fe06c47daae60d4c
