Restrict allowed Postgres versions (via `postgres_allowed_versions_auto`) when Borg Backup is enabled

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/4632

group_vars/matrix_servers

@@ -4203,6 +4203,8 @@ postgres_base_path: "{{ matrix_base_data_path }}/postgres"
 postgres_uid: "{{ matrix_user_uid }}"
 postgres_gid: "{{ matrix_user_gid }}"
 
+postgres_allowed_versions_auto: "{{ backup_borg_supported_postgres_versions | map('int') if backup_borg_enabled | default(false) and backup_borg_postgresql_enabled | default(false) else [] }}"
+
 postgres_connection_username: matrix
 postgres_db_name: matrix