Bump ruff from 0.8.6 to 0.9.1

Bumps [ruff](https://github.com/astral-sh/ruff) from 0.8.6 to 0.9.1.
- [Release notes](https://github.com/astral-sh/ruff/releases)
- [Changelog](https://github.com/astral-sh/ruff/blob/main/CHANGELOG.md)
- [Commits](astral-sh/ruff@0.8.6...0.9.1)

---
updated-dependencies:
- dependency-name: ruff
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements/testing.txt

@@ -7,7 +7,7 @@ pytest==8.3.4
 pytest-asyncio==0.25.2
 pytest-cov==6.0.0
 pytest-icdiff==0.9
-ruff==0.8.6
+ruff==0.9.1
 setuptools==75.8.0
 tox==4.23.2
 tox-gh-actions==3.2.0