CI: minimalistic flake8 backport to re-enable pre-commit and CI

[neteler]

This PR is a minimalistic flake8 settings backport to re-enable pre-commit and CI in relbranch84.

[echoix]

I finally got to cherry pick the commit you had problems with, so better to rebase this branch here, as there will probably be conflicts

[neteler]

I finally got to cherry pick the commit you had problems with

There are still CI errors:

run editorconfig-checker.................................................Failed
- hook id: editorconfig-checker
- exit code: 1

raster/r.reclass/testsuite/test_r_reclass.py:
	8-9: Wrong indent style found (tabs instead of spaces)
vector/v.extract/testsuite/test_v_extract.py:
	8-9: Wrong indent style found (tabs instead of spaces)

2 errors found
scripts/r.reclass.area/testsuite/testrra.py:
	8-9: Wrong indent style found (tabs instead of spaces)
	...

[echoix]

Yep, we've gone a long way since 8.4 in improving the quality.

When discussing offline, I mentioned some of the commits that fixed these issues before that change was made.

So, to also cherry pick (at least some parts of):

• d75a06a (geomorphon)
• Some other tabs/space problems where fixed in e523163
• There’s also 1e86629

That's what I had found before, it might not be enough still for these issues

[neteler]

to also cherry pick (at least some parts of):

I am sorry, this is beyond my git skills (just messed up again my local copy)...

[wenzeslaus]

...also disabling problematic checks is acceptable for older release branches, I would say, even if it means also disabling local pre-commit. Whatever is easier.