⬆️ Bump traitlets from 5.5.0 to 5.6.0 (#392)

Bumps [traitlets](https://github.com/ipython/traitlets) from 5.5.0 to 5.6.0.
- [Release notes](https://github.com/ipython/traitlets/releases)
- [Changelog](https://github.com/ipython/traitlets/blob/main/CHANGELOG.md)
- [Commits](ipython/traitlets@5.5.0...v5.6.0)

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

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>