chore(package): update webpack to version 4.39.0

Closes #45

Author: greenkeeper[bot]

package.json

@@ -41,7 +41,7 @@
     "tslint": "5.16.0",
     "typescript": "^3.4.5",
     "uglifyjs-webpack-plugin": "^2.1.3",
-    "webpack": "4.32.0",
+    "webpack": "4.39.0",
     "webpack-cli": "3.3.2",
     "webpack-dev-server": "3.4.1"
   },