chore(package): update webpack-dev-server to version 3.6.0

Closes #168

Author: greenkeeper[bot]

package.json

@@ -23,6 +23,6 @@
         "copy-webpack-plugin": "4.5.3",
         "webpack": "4.29.6",
         "webpack-cli": "3.1.2",
-        "webpack-dev-server": "3.2.1"
+        "webpack-dev-server": "3.6.0"
     }
 }