Deps: Bump the python-packages group with 3 updates

Bumps the python-packages group with 3 updates: [ruff](https:/astral-sh/ruff), [starlette](https:/encode/starlette) and [uvicorn](https:/encode/uvicorn).


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

Updates `starlette` from 0.38.6 to 0.39.2
- [Release notes](https:/encode/starlette/releases)
- [Changelog](https:/encode/starlette/blob/master/docs/release-notes.md)
- [Commits](encode/starlette@0.38.6...0.39.2)

Updates `uvicorn` from 0.30.6 to 0.31.0
- [Release notes](https:/encode/uvicorn/releases)
- [Changelog](https:/encode/uvicorn/blob/master/CHANGELOG.md)
- [Commits](encode/uvicorn@0.30.6...0.31.0)

---
updated-dependencies:
- dependency-name: ruff
  dependency-type: indirect
  update-type: version-update:semver-patch
  dependency-group: python-packages
- dependency-name: starlette
  dependency-type: indirect
  update-type: version-update:semver-minor
  dependency-group: python-packages
- dependency-name: uvicorn
  dependency-type: indirect
  update-type: version-update:semver-minor
  dependency-group: python-packages
...

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