chore(package): update webpack to version 4.8.2

Closes #6

Author: greenkeeper[bot]

package.json

@@ -47,7 +47,7 @@
     "react": "^16.0.0",
     "react-dom": "^16.0.0",
     "uglifyjs-webpack-plugin": "^1.0.1",
-    "webpack": "^3.8.1"
+    "webpack": "^4.8.2"
   },
   "dependencies": {
     "jest": "^21.2.1"