fixed missing loop variable for headscale user registration task

roles/init-server/tasks/contingent/pkg/headscale.yml

@@ -32,6 +32,7 @@
     cmd: "headscale users create {{ item.username }} -d '{{ item.dname }}' -e '{{ item.email }}'"
   # vars:
   #   default_pfp: ~
+  loop: "{{ tail.users }}"
   register: headscale_registration
   changed_when:
     - "'User created' in headscale_registration.stdout"