Fetch compose file from the git tag and use compose v2

- goauthentik.io/version/<x>/docker-compose.yml only exists for old releases; download lifecycle/container/compose.yml of the version tag instead and always store it as docker-compose.yml
- restart handler used the removed docker_compose (v1) module; switch to community.docker.docker_compose_v2

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tasks/main.yml

@@ -10,7 +10,7 @@
 - name: download authentik compose file
   get_url:
     url: "{{ authentik_source }}/{{ authentik_version }}/{{ authentik_target }}"
-    dest: "{{ authentik_inst }}/{{ authentik_target }}"
+    dest: "{{ authentik_inst }}/docker-compose.yml"
     force: yes
     owner: root
     group: root