www/gitlab: update from 8.8.5 to 8.8.7

8.8.7

• Fix privilege escalation issue with OAuth external users.
• Ensure references to private repos aren't shown to logged-out users.

8.8.6

• Fix visibility of snippets when searching.
• Update omniauth-saml to 1.6.0

Approved by: junovitch (mentor, implicit)
Security: CVE-2016-5697
MFH: 2016Q3