Update dependency file-loader to v6

Author: renovate-bot

package.json

@@ -27,7 +27,7 @@
     "eslint-plugin-jsx-a11y": "2.0.1",
     "eslint-plugin-react": "5.2.2",
     "extract-text-webpack-plugin": "1.0.1",
-    "file-loader": "0.9.0",
+    "file-loader": "6.2.0",
     "filesize": "3.3.0",
     "fs-extra": "0.30.0",
     "gzip-size": "3.0.0",