gitlab: Update chart to 7.4.0.

Change-Id: I44102299c260b265264341e81d624e12ac55a18e
diff --git a/gitlab-system/gitlab.yaml b/gitlab-system/gitlab.yaml
index 1cefe76..a739d91 100644
--- a/gitlab-system/gitlab.yaml
+++ b/gitlab-system/gitlab.yaml
@@ -5,7 +5,7 @@
   namespace: gitlab-system
 spec:
   chart:
-    version: "7.0.3"
+    version: "7.4.0"
     values:
       global:
         appConfig: