Improving yamllint configuration (#11389)

Signed-off-by: Bas Meijer <bas.meijer@enexis.nl>

roles/etcd/tasks/refresh_config.yml

@@ -3,7 +3,7 @@
   template:
     src: etcd.env.j2
     dest: /etc/etcd.env
-    mode: 0640
+    mode: "0640"
   notify: Restart etcd
   when: is_etcd_master and etcd_cluster_setup
 
@@ -11,6 +11,6 @@
   template:
     src: etcd-events.env.j2
     dest: /etc/etcd-events.env
-    mode: 0640
+    mode: "0640"
   notify: Restart etcd-events
   when: is_etcd_master and etcd_events_cluster_setup