Bump socket.io and karma

Bumps [socket.io](https://github.com/socketio/socket.io) to 4.7.5 and updates ancestor dependency [karma](https://github.com/karma-runner/karma). These dependencies need to be updated together.


Updates `socket.io` from 3.1.2 to 4.7.5
- [Release notes](https://github.com/socketio/socket.io/releases)
- [Changelog](https://github.com/socketio/socket.io/blob/4.7.5/CHANGELOG.md)
- [Commits](socketio/socket.io@3.1.2...4.7.5)

Updates `karma` from 6.3.4 to 6.3.20
- [Release notes](https://github.com/karma-runner/karma/releases)
- [Changelog](https://github.com/karma-runner/karma/blob/master/CHANGELOG.md)
- [Commits](karma-runner/karma@v6.3.4...v6.3.20)

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

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