Update dependency eslint-plugin-react to v7.21.4

Author: renovate-bot

package-lock.json

@@ -67,7 +67,7 @@
     "eslint-plugin-jest": "23.20.0",
     "eslint-plugin-jsx-a11y": "6.3.1",
     "eslint-plugin-prettier": "3.1.4",
-    "eslint-plugin-react": "7.20.5",
+    "eslint-plugin-react": "7.21.4",
     "eslint-plugin-react-hooks": "4.0.8",
     "husky": "4.2.5",
     "identity-obj-proxy": "3.0.0",