Bump engine.io from 3.1.5 to 6.2.1 in /public (#16)

Bumps [engine.io](https://github.com/socketio/engine.io) from 3.1.5 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@3.1.5...6.2.1)

---
updated-dependencies:
- dependency-name: engine.io
  dependency-type: indirect
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]