nox: black producing non-equivalent code

[bk521234]

Latest version of black seems to be on the frits. There are a ton of duplicate issues related to unstable formatting,https://github.com/psf/black/issues?q=is%3Aissue+is%3Aopen+label%3A%22unstable+formatting%22
and a pinned issue where most of the conversation is happening, psf/black#1629

I saw this message when running nox

nox > Running session blacken-3.8.1
nox > Creating virtualenv using python3.8 in /home/salvidor/dev/python/bk-fables/.nox/blacken-3-8-1
nox > pip install black
nox > black fables tests noxfile.py setup.py
error: cannot format /home/bk/dev/python/bk-fables/tests/integration/test_it_parses_files.py: INTERNAL ERROR: Black produced code that is not equivalent to the source.  Please report a bug on https://github.com/psf/black/issues.  This diff might be helpful: /tmp/blk_8ca_wv62.log
Oh no! 💥 💔 💥
21 files left unchanged, 1 file failed to reformat.
nox > Command black fables tests noxfile.py setup.py failed with exit code 123
nox > Session blacken-3.8.1 failed.