The project uses Black because it is a code formatter that leaves a clean, even and professional finish. In addition to this, it helps much more to its readability and is strongly recommended in case you want to contribute to apply it in your pull request.
Flake8 is a Python library that wraps PyFlakes, pycodestyle and Ned Batchelder’s McCabe script. It is a great toolkit for checking your code base against coding style (PEP8), programming errors (like “library imported but unused” and “Undefined name”) and many other control flow operations. It is strongly recommended in case you want to contribute to apply it in your pull request.