www/gitlab-ce: major upgrade to 16.3.0

Make sure you install this version as it will be required for all
further upgrades:
https://gitlab.com/gitlab-org/gitlab/-/blob/master/doc/update/index.md#upgrade-paths

Changelog:
https://about.gitlab.com/releases/2023/07/22/gitlab-16-2-released/
https://about.gitlab.com/releases/2023/08/22/gitlab-16-3-released/