fix: set default value for POSTGRES_PORT in docker-compose.yml

docker-compose.yml

@@ -11,7 +11,7 @@ services:
     volumes:
        - postgres_data:/data/postgres
     ports:
-      - "${POSTGRES_PORT}:5432"
+      - "${POSTGRES_PORT:-5432}:5432"
     networks:
       - postgres
     restart: unless-stopped