fixed syntax error in nat_server role

**service: iptables ** should be service: name:iptables

roles/nat_server/tasks/main.yml

@@ -41,7 +41,8 @@
   register: rule_changed
 
 - name: restore rules
-  service: iptables
+  service: 
+    name: iptables
     state: reloaded
   become: true
   become_user: root