GitLab: drop duplicate link

wiki/src/contribute/working_together/GitLab.mdwn

@@ -512,8 +512,7 @@ administrate this GitLab instance.
 If you need to do something in GitLab and you appear to lack the
 needed credentials, please ask the Tails
 [[system administrators|working_together/roles/sysadmins#communication]]
-[[tails-sysadmins@boum.org|about/contact#tails-sysadmins]] to grant
-you more power.
+to grant you more power.
 
 For example, you will need "Reporter" access on the [[!tails_gitlab
 tails/tails]] project in order to add labels or assign issues.