Add configuration for Flake8.

[HexDecimal]

The main differences from the defaults are enabling the opinionated bugbear codes and excluding the vendored sources.

[agronholm]

Flake8 was meant to be run through pre-commit which already excludes the vendored sources.

[codecov]

Codecov Report

Base: 69.16% // Head: 69.16% // No change to project coverage 👍

Coverage data is based on head (c3cdacb) compared to base (81471ec).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##           publicapi     #476   +/-   ##
==========================================
  Coverage      69.16%   69.16%           
==========================================
  Files             11       11           
  Lines            989      989           
==========================================
  Hits             684      684           
  Misses           305      305           

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[HexDecimal]

I sometimes run it manually and it flags the vendored files when I do.

[agronholm]

So, don't? Running flake8 manually only runs the flake8 checks and not the rest of the checks that need to pass for CI to pass. Just instead of flake8, run pre-commit run -a flake8 if you only want to run flake8 checks.

[agronholm]

What makes this even more important is that, once I can, I will switch from the official flake8 to pyproject-flake8 so I can ditch setup.cfg entirely.

[HexDecimal]

I mean things like the --max-complexity option are reasonable to be checked on manually.

[agronholm]

Aside from the vendor exclusion, what's the rationale for these specific settings?

[HexDecimal]

Git checks out files with CLRF on Windows, so I can't install the pre commit hooks unless I branch off of #474.

[HexDecimal]

Aside from the vendor exclusion, what's the rationale for these specific settings?

select = B,B9,E,F,C9 mostly copied from the default settings from the Flake8 docs. W is excluded since Black handles those issues. B9 enables the extra bugbear codes which already pass, B enables the usual bugbear codes.
https://flake8.pycqa.org/en/latest/user/options.html#cmdoption-flake8-select

extend-ignore = E203 required for Black or else you can't have math in square brackets. Using extend-ignore will not replace the default commonly ignored codes which would conflict with Black.

[henryiii]

This is now closable, as Ruff is used instead of flake8.