feat: adapt role redis for backports

peertube.yml

@@ -7,6 +7,9 @@
   roles:
     - nodejs
     - yarn
-    - redis
+    - backports
+    - name: redis
+      vars:
+        redis_backports: true
     - postgres
     - peertube

roles/redis/tasks/main.yml

@@ -5,6 +5,7 @@
     name: redis
     state: present
     update_cache: true
+    default_release: "{{ omit if redis_backports is undefined }}"
 
 - name: Start redis service
   ansible.builtin.service: