Remove flake8 upper constraint

[pawelad]

Hi!

Is there any reason for the flake8 upper constraint?

flake8-django/pyproject.toml

Line 27 in 808284f

flake8 = ">=3.8.4,<6"

Version 6 of flake8 was recently released (https://flake8.pycqa.org/en/latest/release-notes/6.0.0.html) but I can't upgrade because of this upper constraint.

Here are some helpful articles that (among other things) lay out why packages shouldn't provide upper version constraints of it's dependencies:

• https://hynek.me/articles/semver-will-not-save-you/
• https://iscinumpy.dev/post/bound-version-constraints/
• https://bernat.tech/posts/version-numbers/

[pawelad]

Related to #103, but I'd still vote to remove the <7 constraint from there.

[pietzschke]

+1 same situation with the new v7 version

[sevdog]

This should also be addressed after #134