With version 13.10.0 upstream abandoned the workhorse project and moved
it's code to the workhorse/ folder inside the gitlab project.
So, starting with www-apps/gitlab-13.10.0, there will be no package www-servers/gitlab-workhorse anymore and the workhorse code will be installed by www-apps/gitlab, too.
So, starting with www-apps/gitlab-13.10.0, there will be no package www-servers/gitlab-workhorse anymore and the workhorse code will be installed by www-apps/gitlab, too.