fix(package): update url-loader to version 3.0.0

Closes #250

Author: greenkeeper[bot]

Diff for: package.json

@@ -75,7 +75,7 @@
     "sass-loader": "^7.0.1",
     "sendmail": "^1.2.0",
     "style-loader": "^0.21.0",
-    "url-loader": "^1.0.0",
+    "url-loader": "^3.0.0",
     "webpack": "^4.0.0",
     "webpack-bundle-analyzer": "^2.9.2",
     "webpack-cli": "^3.0.0",