updated role to work with ansible 2.6

tasks/main.yml

@@ -31,7 +31,7 @@
   template:
     src: zonefile.db.j2
     dest: "/etc/powerdns/tpl/{{ item }}"
-  with_items: "{{ dnsserver.zones.keys() }}"
+  with_items: "{{ dnsserver.zones.keys()|list }}"
   register: zonefilestask
   notify:
   - copy zone