fix(package): update assets-webpack-plugin to version 3.9.2

Closes #239

Author: greenkeeper[bot]

package.json

@@ -49,7 +49,7 @@
   "author": "Nebo15 <support@nebo15.com> (http://nebo15.com/)",
   "license": "MIT",
   "dependencies": {
-    "assets-webpack-plugin": "3.4.0",
+    "assets-webpack-plugin": "3.9.2",
     "autoprefixer": "7.1.2",
     "babel": "6.23.0",
     "babel-core": "6.25.0",