Bump dulwich from 0.22.1 to 0.22.6

Bumps [dulwich](https://github.com/dulwich/dulwich) from 0.22.1 to 0.22.6.
- [Release notes](https://github.com/dulwich/dulwich/releases)
- [Changelog](https://github.com/jelmer/dulwich/blob/master/NEWS)
- [Commits](https://github.com/dulwich/dulwich/compare/dulwich-0.22.1...dulwich-0.22.6

)

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

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