Update dependency eslint-loader to v4

Author: renovate[bot]

package.json

@@ -35,7 +35,7 @@
     "eslint": "^3.6.0",
     "eslint-config-airbnb": "^12.0.0",
     "eslint-config-react-native": "^1.6.0",
-    "eslint-loader": "^1.3.0",
+    "eslint-loader": "^4.0.0",
     "eslint-plugin-babel": "^3.2.0",
     "eslint-plugin-import": "^2.0.1",
     "eslint-plugin-jsx-a11y": "^2.2.3",