Bump @oclif/plugin-plugins from 5.0.19 to 5.0.21

Bumps [@oclif/plugin-plugins](https://github.com/oclif/plugin-plugins) from 5.0.19 to 5.0.21.
- [Release notes](https://github.com/oclif/plugin-plugins/releases)
- [Changelog](https://github.com/oclif/plugin-plugins/blob/main/CHANGELOG.md)
- [Commits](oclif/plugin-plugins@5.0.19...5.0.21)

---
updated-dependencies:
- dependency-name: "@oclif/plugin-plugins"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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