Update www/gitlab-ce to 11.2.3.
For a detailed changelog please see here:
https://about.gitlab.com/2018/08/22/gitlab-11-2-released/
https://about.gitlab.com/2018/08/23/gitlab-11-2-1-released/
https://about.gitlab.com/2018/08/28/security-release-gitlab-11-dot-2-dot-2-released/
Approved by: mentors (implicit)