chore(package): update webpack to version 4.7.0

Closes #33

Author: greenkeeper[bot]

Diff for: package.json

@@ -60,7 +60,7 @@
     "prettier": "^1.5.2",
     "remark-cli": "^5.0.0",
     "remark-preset-lint-itgalaxy": "^12.0.0",
-    "webpack": "^3.0.0",
+    "webpack": "^4.7.0",
     "webpack-dev-middleware": "^1.0.0",
     "webpack-hot-middleware": "^2.0.0"
   },