Bump ws and maildev in /tests/UI

Bumps [ws](https://github.com/websockets/ws) and [maildev](https://github.com/maildev/maildev). These dependencies needed to be updated together.

Updates `ws` from 8.11.0 to 8.18.0
- [Release notes](https://github.com/websockets/ws/releases)
- [Commits](websockets/ws@8.11.0...8.18.0)

Updates `maildev` from 2.1.0 to 2.2.1
- [Release notes](https://github.com/maildev/maildev/releases)
- [Commits](maildev/maildev@v2.1.0...v2.2.1)

---
updated-dependencies:
- dependency-name: ws
  dependency-type: indirect
- dependency-name: maildev
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>