fix(deps): update dependency url-loader to v4 (#62)

Co-authored-by: Renovate Bot <[email protected]>

BREAKING CHANGE: url-loader configuration regarding mime types has changed for some more obscure mime types.  It's unlikely that any known consumers of this package have any migrating to do.

Author: renovate[bot]

package-lock.json

@@ -69,7 +69,7 @@
     "sass-loader": "6.0.7",
     "source-map-loader": "0.2.4",
     "style-loader": "1.1.3",
-    "url-loader": "2.3.0",
+    "url-loader": "4.0.0",
     "webpack": "4.42.1",
     "webpack-bundle-analyzer": "3.6.1",
     "webpack-cli": "3.3.11",