www/gitlab: Update from 9.3.10 to 9.3.11

Changelog: https://github.com/gitlabhq/gitlabhq/blob/v9.3.11/CHANGELOG.md

This fixes an XSS security issue. The mentioned security issues in
the gems are already fixed by updates of them gems itself.

Security: CVE-2017-5029
Security: CVE-2016-4738
Security: https://vuxml.FreeBSD.org/freebsd/6a177c87-9933-11e7-93f7-d43d7e971a1b.html