gitlab: Update chart to 7.6.0.

Change-Id: If8b9d432999cd9849cbd263df6e331c8efa34d60
diff --git a/gitlab-system/gitlab.yaml b/gitlab-system/gitlab.yaml
index a739d91..7116f5d 100644
--- a/gitlab-system/gitlab.yaml
+++ b/gitlab-system/gitlab.yaml
@@ -5,7 +5,7 @@
   namespace: gitlab-system
 spec:
   chart:
-    version: "7.4.0"
+    version: "7.6.0"
     values:
       global:
         appConfig: