fix: upgrade multiple dependencies with Snyk

Snyk has created this PR to upgrade:
  - react from 16.11.0 to 16.13.1.
    See this package in NPM: https://www.npmjs.com/package/react
  - react-dom from 16.11.0 to 16.13.1.
    See this package in NPM: https://www.npmjs.com/package/react-dom

See this project in Snyk:
https://app.snyk.io/org/ashishpatel0720/project/5df45c19-cb3b-41ea-9992-3c613a47d453?utm_source=github&utm_medium=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -12,8 +12,8 @@
     "@docusaurus/core": "^2.0.0-alpha.33",
     "@docusaurus/preset-classic": "^2.0.0-alpha.33",
     "classnames": "^2.2.6",
-    "react": "^16.8.4",
-    "react-dom": "^16.8.4"
+    "react": "^16.13.1",
+    "react-dom": "^16.13.1"
   },
   "browserslist": {
     "production": [