Bump cookie, express and socket.io in /slides

Bumps [cookie](https://github.com/jshttp/cookie) to 0.7.1 and updates ancestor dependencies [cookie](https://github.com/jshttp/cookie), [express](https://github.com/expressjs/express) and [socket.io](https://github.com/socketio/socket.io). These dependencies need to be updated together.


Updates `cookie` from 0.6.0 to 0.7.1
- [Release notes](https://github.com/jshttp/cookie/releases)
- [Commits](jshttp/cookie@v0.6.0...v0.7.1)

Updates `express` from 4.20.0 to 4.21.1
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/4.21.1/History.md)
- [Commits](expressjs/express@4.20.0...4.21.1)

Updates `socket.io` from 2.5.0 to 4.8.0
- [Release notes](https://github.com/socketio/socket.io/releases)
- [Changelog](https://github.com/socketio/socket.io/blob/main/CHANGELOG.md)
- [Commits](https://github.com/socketio/socket.io/compare/2.5.0...socket.io@4.8.0)

---
updated-dependencies:
- dependency-name: cookie
  dependency-type: indirect
- dependency-name: express
  dependency-type: direct:development
- dependency-name: socket.io
  dependency-type: direct:development
...

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Author: dependabot[bot]