Bump socket.io from 2.2.0 to 2.4.0

Bumps [socket.io](https://github.com/socketio/socket.io) from 2.2.0 to 2.4.0.
- [Release notes](https://github.com/socketio/socket.io/releases)
- [Changelog](https://github.com/socketio/socket.io/blob/2.4.0/CHANGELOG.md)
- [Commits](https://github.com/socketio/socket.io/compare/2.2.0...2.4.0)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -10,7 +10,7 @@
     "react": "^16.8.6",
     "react-dom": "^16.8.6",
     "react-scripts": "3.0.1",
-    "socket.io": "^2.2.0",
+    "socket.io": "^2.4.0",
     "twitter": "^1.7.1"
   },
   "scripts": {