unbound: use handlers

Only restart unbound if the configuration
was actually updated.

roles/unbound/handlers/main.yml

@@ -0,0 +1,4 @@
+- name: restart unbound
+  systemd:
+    state: restarted
+    name: unbound

roles/unbound/tasks/main.yml

@@ -24,20 +24,18 @@
     src: unbound-control.conf.j2
     dest: /etc/unbound/unbound.conf.d/unbound-control.conf
     mode: 0644
+  notify: restart unbound
 
 - name: setup main unbound config file
   template:
     src: unbound.conf.j2
     dest: /etc/unbound/unbound.conf
     mode: 0644
+  notify: restart unbound
 
 - name: setup recursive DNS server config
   template:
     src: recursive.conf.j2
     dest: /etc/unbound/unbound.conf.d/recursive.conf
     mode: 0644
-
-- name: restart unbound after editing config
-  systemd:
-    state: restarted
-    name: unbound
+  notify: restart unbound