build(deps): bump ruff in the test-and-lint-dependencies group

Bumps the test-and-lint-dependencies group with 1 update: [ruff](https://github.com/astral-sh/ruff).


Updates `ruff` from 0.6.8 to 0.6.9
- [Release notes](https://github.com/astral-sh/ruff/releases)
- [Changelog](https://github.com/astral-sh/ruff/blob/main/CHANGELOG.md)
- [Commits](astral-sh/ruff@0.6.8...0.6.9)

---
updated-dependencies:
- dependency-name: ruff
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: test-and-lint-dependencies
...

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

requirements/lint.txt

@@ -6,5 +6,5 @@
 # Lint tools
 # (We are not so interested in the specific versions of the tools: the versions
 # are pinned to prevent unexpected linting failures when tools update)
-ruff==0.6.8
+ruff==0.6.9
 mypy==1.11.2