PEP8 was renamed to pycodestyle; this issue explains why:
https://github.com/PyCQA/pycodestyle/issues/466
This commit changes our tests to use pycodestyle instead of pep8.
It also means:
- making a couple of whitespace changes to appease the linter
- disabling warnings for bare `Except`s (ie `Except` instead of `Except
ValueError`) – this seems like a sensible thing to catch but I’m not
going to make meaningful code changes in this commit