Upgrade Flake8 to v6.1.0

[Mr0grog]

Earlier versions of flake8 do not support Python 3.12. Part of #123.

[Mr0grog]

Well, this version of flake8 does not support Python < 3.8. Those versions are all end-of-life at this point (https://devguide.python.org/versions/) so this is probably OK. Will need to update the checks and classifiers in setup.py here, too:

wayback/setup.py

Lines 7 to 23 in 1ea1223

	# NOTE: This file must remain Python 2 compatible for the foreseeable future,
	# to ensure that we error out properly for people with outdated setuptools
	# and/or pip.
	min_version = (3, 6)
	if sys.version_info < min_version:
	error = """
	wayback does not support Python {0}.{1}.
	Python {2}.{3} and above is required. Check your Python version like so:
	python3 --version
	This may be due to an out-of-date pip. Make sure you have pip >= 9.0.1.
	Upgrade pip like so:
	pip install --upgrade pip
	""".format(*(sys.version_info[:2] + min_version))
	sys.exit(error)

[Mr0grog]

Also worth noting: Google Colab has since updated to Python 3.10, so this shouldn't break any Colab stuff.

[Mr0grog]

Trying an alternative by splitting out test dependencies from other dev dependencies, kind of like how we handle docs. Maybe more complex than is healthy, but lets us continue being Python 3.6 compatible (sort of).