Update docker-compose to use named volume for PostgreSQL

postgressql/docker-compose.yml

@@ -12,8 +12,12 @@ services:
       PUID: 1026
       PGID: 100
     volumes:
-      - ./postgresql_data:/var/lib/postgresql/data:rw
+      - postgresql_data:/var/lib/postgresql/data:rw
     ports:
       - 5432:5432
     restart: always
     network_mode: "bridge"
+
+volumes:
+  postgresql_data:
+    driver: local