Upgrade mautrix-facebook to the new Postgres-only version

I had intentionally held it back in 39ea3496a4
until:
- it received more testing (there were a few bugs during the
migration, but now it seems OK)
- this migration guide was written

group_vars/matrix_servers

@@ -208,7 +208,8 @@ matrix_mautrix_facebook_login_shared_secret: "{{ matrix_synapse_ext_password_pro
 
 matrix_mautrix_facebook_bridge_presence: "{{ matrix_synapse_use_presence if matrix_synapse_enabled else true }}"
 
-# Postgres is the default, except if not using `matrix_postgres` (internal postgres)
+# We'd like to force-set people with external Postgres to SQLite, so the bridge role can complain
+# and point them to a migration path.
 matrix_mautrix_facebook_database_engine: "{{ 'postgres' if matrix_postgres_enabled else 'sqlite' }}"
 matrix_mautrix_facebook_database_password: "{{ matrix_synapse_macaroon_secret_key | password_hash('sha512', 'mau.fb.db') | to_uuid }}"