Update gitlab-markup to 1.7.0 and document Python3 requirements
We've been running docutils
to render reStructuredText markup with Python 3 by patching current gitlab-markup
gem in Omnibus GitLab (see original merge request: omnibus-gitlab!968 (merged))
This patch is no longer needed as we merged Python 3 support natively in gitlab-markup!9 (merged).
We need to update the gem in our codebase and remove the patch from omnibus-gitlab. Additionally we should document our python requirements and how to run it with GitLab in development.