Bump engine.io and browser-sync in /frontend

Bumps [engine.io](https://github.com/socketio/engine.io) to 6.2.1 and updates ancestor dependency [browser-sync](https://github.com/BrowserSync/browser-sync). These dependencies need to be updated together.


Updates `engine.io` from 3.5.0 to 6.2.1
- [Release notes](https://github.com/socketio/engine.io/releases)
- [Changelog](https://github.com/socketio/engine.io/blob/main/CHANGELOG.md)
- [Commits](socketio/engine.io@3.5.0...6.2.1)

Updates `browser-sync` from 2.26.14 to 2.27.10
- [Release notes](https://github.com/BrowserSync/browser-sync/releases)
- [Changelog](https://github.com/BrowserSync/browser-sync/blob/master/CHANGELOG.md)
- [Commits](BrowserSync/browser-sync@v2.26.14...v2.27.10)

---
updated-dependencies:
- dependency-name: engine.io
  dependency-type: indirect
- dependency-name: browser-sync
  dependency-type: direct:development
...

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