fix webpack version

Author: eloytoro

package.json

@@ -43,7 +43,7 @@
     "nsp": "^3.1.0",
     "pre-commit": "^1.2.2",
     "standard-version": "^4.3.0",
-    "webpack": "^3.11.0",
+    "webpack": "^4.0.0",
     "webpack-defaults": "^1.6.0"
   },
   "files": [