Use PORT instead of UPAAS_PORT for listen port

docker-compose.yml

@@ -7,8 +7,7 @@ services:
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
       - upaas-data:/var/lib/upaas
-    environment:
-      - UPAAS_PORT=8080
+    # environment:
       # Optional: uncomment to enable debug logging
       # - DEBUG=true
       # Optional: Sentry error reporting