Run flake8 without an env on Github CI
In a way, this addresses https://github.com/zheller/flake8-quotes/issues/117, since it forces the Python that runs flake8 onto 'oldest supported', currently 3.8.
In a way, this addresses https://github.com/zheller/flake8-quotes/issues/117, since it forces the Python that runs flake8 onto 'oldest supported', currently 3.8.