Bump towncrier from 22.12.0 to 23.6.0

Bumps [towncrier](https://github.com/twisted/towncrier) from 22.12.0 to 23.6.0.
- [Release notes](https://github.com/twisted/towncrier/releases)
- [Changelog](https://github.com/twisted/towncrier/blob/trunk/NEWS.rst)
- [Commits](twisted/towncrier@22.12.0...23.6.0)

---
updated-dependencies:
- dependency-name: towncrier
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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