Remove flake8 config from setup.cfg

ruff doesn’t read `setup.cfg` so the rules defined there are redundant.
This is a hangover from when we used to use `flake8` directly.

I’ve copied some of the rules into pyproject.toml

Selected rules:
- B902 and implemented in ruff as N804 and N805. Only copying N804
  because N805 gets tripped up by sqlalchemy/sqlalchemy#9213
- E203 still in preview in ruff, add a note to include it later

Ignored rules:
- W503 and W504 aren’t likely to be implemented in ruff
  astral-sh/ruff#4125
- E203 is still in preview https://docs.astral.sh/ruff/rules/whitespace-before-punctuation/
  so we don’t need to worry about ignoring it (and maybe it will be fit
  for purpose once it’s out of preview)

Cyclomatic complexity:
- this repo has it set to 8, but everywhere else we use the default (10)
  so let’s not copy that into `pyproject.toml`

notifications_utils/version_tools/pyproject.toml

@@ -20,6 +20,7 @@ lint.select = [
     "ISC",  # flake8-implicit-str-concat
     "RSE",  # flake8-raise
     "PIE",  # flake8-pie
+    "N804",  # First argument of a class method should be named `cls`
 ]
 lint.ignore = []
 exclude = [

setup.cfg

@@ -1,18 +1,2 @@
 [tool:pytest]
 xfail_strict=true
-
-[flake8]
-# B901, B902 are opinionated warnings from flake8-bugbear, so must be added to
-# the `select` in order to work. Since `select` acts as an allowlist, every
-# other check has to be specified here too.
-# Rule definitions: http://flake8.pycqa.org/en/latest/user/error-codes.html
-select=C, E, F, W, B, B901, B902
-
-# W503: line break before binary operator
-# W504: line break after binary operator
-# E203: space before/after :
-ignore = W503, W504, E203
-
-exclude = venv*,__pycache__,cache
-max-complexity = 8
-max-line-length = 120