Update file-loader to the latest version 🚀 (#1498)

* chore(package): update file-loader to version 6.0.0

* chore(package): update lockfile package-lock.json

Co-authored-by: greenkeeper[bot] <23040076+greenkeeper[bot]@users.noreply.github.com>

Author: greenkeeper[bot]

package-lock.json

@@ -88,7 +88,7 @@
     "eslint": "6.8.0",
     "eslint-plugin-jest": "23.8.2",
     "eslint-plugin-react": "7.19.0",
-    "file-loader": "4.3.0",
+    "file-loader": "6.0.0",
     "http-server": "0.12.0",
     "jest": "24.8.0",
     "marked": "0.8.0",