One of the tests requires Python 3.9 or higher to run. Mark the test
to be skipped if running Python less than 3.9.

Closes #1777

chore: generate artifacts for the docs build in the CI

Add some docs for getting the status of a merge_request rebase

Add and document (some of the) optional parameters that can be done
for a `project.merge_requests.get()`

Closes #1775

Rename the merge request related documentation files to match the code
files. This will make it easier to find the documentation quickly.

Rename:
  `docs/gl_objects/mrs.rst -> `docs/gl_objects/merge_requests.rst`
  `docs/gl_objects/mr_approvals.rst -> `docs/gl_objects/merge_request_approvals.rst`

When building the docs store the created documentation as an artifact
so that it can be viewed.

This will create a html-docs.zip file which can be downloaded
containing the contents of the `build/sphinx/html/` directory. It can
be downloaded, extracted, and then viewed. This can be useful in
reviewing changes to the documentation.

See https://github.com/actions/upload-artifact for more information on
how this works.

fix: stop encoding '.' to '%2E'

chore(deps): update pre-commit hook alessandrojcm/commitlint-pre-commit-hook to v6