Update package.json

Author: xudafeng

package.json

@@ -42,7 +42,7 @@
     "classnames": "^2.2.5",
     "cross-env": "^5.1.1",
     "css-loader": "^0.28.8",
-    "datahub-proxy-middleware": "3",
+    "datahub-proxy-middleware": "4",
     "eslint": "^4.10.0",
     "eslint-config-standard": "^11.0.0-beta.0",
     "eslint-loader": "^2.0.0",