Merge branch 'workhorse-0.7.11' into 'master'

Use gitlab-workhorse 0.7.11

Versions 0.7.9 and 0.7.10 crash on previously valid 'authBackend'
settings.

I don't know how many people are affected by this, 'normal' Omnibus
installations are not. (If they were gitlab.com would have stopped
working :) ). Still this is something we should not ship.
Unfortunately 8-11-stable uses 0.7.10 (but 8.11.0 does not). So I
think we need to put this in the next 8.11 patch release.

See merge request !5983

GITLAB_WORKHORSE_VERSION

@@ -1 +1 @@
-0.7.10
+0.7.11

doc/install/installation.md

@@ -397,7 +397,7 @@ If you are not using Linux you may have to run `gmake` instead of
     cd /home/git
     sudo -u git -H git clone https://gitlab.com/gitlab-org/gitlab-workhorse.git
     cd gitlab-workhorse
-    sudo -u git -H git checkout v0.7.10
+    sudo -u git -H git checkout v0.7.11
     sudo -u git -H make
 
 ### Initialize Database and Activate Advanced Features