[flake8-pytest-style] Allow for loops with empty bodies (PT012, PT031)

[MichaReiser]

Summary

This PR stabilizes the behavior change introduced in #15542 to allow
for statements with an empty body in pytest.raises and pytest.warns with statements.

This raised an error before but is now allowed:

with pytest.raises(KeyError, match='unknown'):
    async for _ in gpt.generate(gpt_request):
        pass

The same applies to

with pytest.raises(KeyError, match='unknown'):
    async for _ in gpt.generate(gpt_request):
        ...

There have been now new issues or PRs related to PT012 or PT031 since this behavior change was introduced in ruff 0.9.3 (January 23rd).

[codspeed-hq]

CodSpeed Performance Report

Merging #16678 will degrade performances by 10.5%

_{Comparing micha/pytest-empty-for-loop (ec38e73) with micha/ruff-0.10 (e9bfdfd)}

Summary

❌ 1 regressions
✅ 31 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	red_knot_check_file[incremental]	4.9 ms	5.5 ms	-10.5%

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[ntBre]

Nice, I think it made sense to move these up to ## What it does too.