Update dependency file-loader to v4.2.0

Author: renovate-bot

package.json

@@ -85,7 +85,7 @@
     "eslint-plugin-jest": "22.14.1",
     "eslint-plugin-prettier": "3.1.0",
     "eslint-watch": "6.0.0",
-    "file-loader": "4.1.0",
+    "file-loader": "4.2.0",
     "html-webpack-plugin": "3.2.0",
     "husky": "3.0.2",
     "identity-obj-proxy": "3.0.0",