Upgrade postgres-backup (v17-7 -> v17-8)

requirements.yml

@@ -46,7 +46,7 @@
   version: v17.6-0
   name: postgres
 - src: git+https://github.com/mother-of-all-self-hosting/ansible-role-postgres-backup.git
-  version: v17-7
+  version: v17-8
   name: postgres_backup
 - src: git+https://github.com/mother-of-all-self-hosting/ansible-role-prometheus.git
   version: v3.5.0-1