always add pf role to openbsd hosts

roles/base/tasks/OpenBSD.yml

@@ -25,3 +25,11 @@
     name: sndiod
     enabled: false
     state: stopped
+
+- name: install os specific roles
+  include_role:
+    name: "{{ role }}"
+  with_items:
+    - pf
+  loop_control:
+    loop_var: role