build(deps): bump socket.io in /packages/browser-sync

Bumps [socket.io](https://github.com/socketio/socket.io) from 2.1.1 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](socketio/socket.io@2.1.1...2.4.0)

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

packages/browser-sync/package.json

@@ -60,7 +60,7 @@
     "serve-index": "1.9.1",
     "serve-static": "1.13.2",
     "server-destroy": "1.0.1",
-    "socket.io": "2.1.1",
+    "socket.io": "2.4.0",
     "ua-parser-js": "^0.7.18",
     "yargs": "^15.4.1"
   },