Bump doorkeeper from 5.5.4 to 5.6.0 (#19163)

Bump doorkeeper from 5.5.4 to 5.6.0 (#19163)

Bumps [doorkeeper](https://github.com/doorkeeper-gem/doorkeeper) from 5.5.4 to 5.6.0.
- [Release notes](https://github.com/doorkeeper-gem/doorkeeper/releases)
- [Changelog](https://github.com/doorkeeper-gem/doorkeeper/blob/main/CHANGELOG.md)
- [Commits](https://github.com/doorkeeper-gem/doorkeeper/compare/v5.5.4...v5.6.0)

---
updated-dependencies:
- dependency-name: doorkeeper
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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