Update dependency eslint-loader to v4

Signed-off-by: Renovate Bot <bot@renovateapp.com>

Author: renovate-bot

package-lock.json

@@ -49,7 +49,7 @@
     "classnames": "^2.2.6",
     "eslint": "^6.8.0",
     "eslint-config-airbnb": "^18.2.0",
-    "eslint-loader": "^2.2.1",
+    "eslint-loader": "^4.0.2",
     "eslint-plugin-import": "^2.22.1",
     "eslint-plugin-jsx-a11y": "^6.3.1",
     "eslint-plugin-react": "^7.21.2",