redis package must be installed before we try to start it

roles/copr/backend/tasks/main.yml

@@ -9,6 +9,7 @@
   - copr-backend
   - python-novaclient
   - obs-signd # TODO: remove, since it will be installed as dependency by copr-backend
+  - redis # we need this to start the service in next step
 
 - name: enable and start redis  # TODO: .service in copr-backend should depend on redis
   service: name=redis enabled=yes state=started