Deps: Bump black in /backport-pull-request in the dependencies group

Bumps the dependencies group in /backport-pull-request with 1 update: [black](https://github.com/psf/black).


Updates `black` from 24.3.0 to 24.4.0
- [Release notes](https://github.com/psf/black/releases)
- [Changelog](https://github.com/psf/black/blob/main/CHANGES.md)
- [Commits](psf/black@24.3.0...24.4.0)

---
updated-dependencies:
- dependency-name: black
  dependency-type: indirect
  update-type: version-update:semver-minor
  dependency-group: dependencies
...

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