Bump ruff from 0.6.6 to 0.6.8

Bumps [ruff](https://github.com/astral-sh/ruff) from 0.6.6 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@0.6.6...0.6.8)

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

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

Author: dependabot[bot]

requirements-tests.txt

@@ -5,4 +5,4 @@ pydantic[email]
 pytest >=7.1.3,<9.0.0
 pytest-asyncio
 pytest-cov >=2.12.0,<6.0.0
-ruff ==0.6.6
+ruff ==0.6.8