Bump mkdocs-macros-plugin from 0.4.18 to 0.5.5

Bumps [mkdocs-macros-plugin](https://github.com/fralau/mkdocs_macros_plugin) from 0.4.18 to 0.5.5.
- [Release notes](https://github.com/fralau/mkdocs_macros_plugin/releases)
- [Changelog](https://github.com/fralau/mkdocs_macros_plugin/blob/master/CHANGELOG.md)
- [Commits](https://github.com/fralau/mkdocs_macros_plugin/compare/v0.4.18...v0.5.5)

---
updated-dependencies:
- dependency-name: mkdocs-macros-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

docs/requirements.txt

@@ -1,7 +1,7 @@
 mkdocs==1.1.2
 mkdocs-material==7.1.7
 pymdown-extensions==8.2
-mkdocs-macros-plugin==0.4.18
+mkdocs-macros-plugin==0.5.5
 mkdocs-awesome-pages-plugin==2.4.0
 mkdocs-redirects==1.0.1
 mkdocs-git-revision-date-localized-plugin==0.9.2