Update flake8 to 3.9.1#83

pyup-bot wants to merge 1 commit intomasterlimberger/libpythonpro:masterfrom

pyup-update-flake8-3.8.4-to-3.9.1limberger/libpythonpro:pyup-update-flake8-3.8.4-to-3.9.1Copy head branch name to clipboard