ops: do not publish demo db port

compose/demo.yml

@@ -9,8 +9,6 @@ services:
     image: postgres:16
     container_name: likwid-demo-db
     restart: unless-stopped
-    ports:
-      - "${DB_PORT:-5433}:5432"
     environment:
       POSTGRES_USER: ${POSTGRES_USER:-likwid_demo}
       POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-demo_secret_change_me}