mgrote_users: fix filter (#161)

Reviewed-on: #161
Co-authored-by: Michael Grote <michael.grote@posteo.de>
Co-committed-by: Michael Grote <michael.grote@posteo.de>

roles/mgrote_users/tasks/main.yml

@@ -1,7 +1,7 @@
 ---
 - name: set groups as list
   ansible.builtin.set_fact:
-    groups_as_list: "{{ (groups_as_list | default([]) + item.groups.split(',')) | map('trim') | list | sort | unique }}"
+    groups_as_list: "{{ (((((groups_as_list | default([]) + item.groups.split(','))) | map('trim')) | list) | sort) | unique }}"
   loop: '{{ users }}'
   when: item.groups is defined