gitlab: Update chart to version 7.9.1.

Change-Id: I623ad25e09cbc36e4ede1c25766c83a8c25d1ea2
diff --git a/gitlab-system/gitlab.yaml b/gitlab-system/gitlab.yaml
index 6e83105..928a84d 100644
--- a/gitlab-system/gitlab.yaml
+++ b/gitlab-system/gitlab.yaml
@@ -5,7 +5,7 @@
   namespace: gitlab-system
 spec:
   chart:
-    version: "7.7.2"
+    version: "7.9.1"
     values:
       global:
         appConfig: