Bump ruff from 0.6.7 to 0.6.8

Bumps [ruff](https://github.com/astral-sh/ruff) from 0.6.7 to 0.6.8.
- [Release notes](https://github.com/astral-sh/ruff/releases)
- [Changelog](https://github.com/astral-sh/ruff/blob/main/CHANGELOG.md)
- [Commits](astral-sh/ruff@0.6.7...0.6.8)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements-test.txt

@@ -1,3 +1,3 @@
 tox==4.20.0
 coverage==7.6.1
-ruff==0.6.7
+ruff==0.6.8