Bump engine.io and karma in /openhtf/output/web_gui (#1025)

Bumps [engine.io](https://github.com/socketio/engine.io) and [karma](https://github.com/karma-runner/karma). These dependencies needed to be updated together.

Updates `engine.io` from 1.8.2 to 6.2.0
- [Release notes](https://github.com/socketio/engine.io/releases)
- [Changelog](https://github.com/socketio/engine.io/blob/main/CHANGELOG.md)
- [Commits](socketio/engine.io@1.8.2...6.2.0)

Updates `karma` from 1.4.1 to 6.4.0
- [Release notes](https://github.com/karma-runner/karma/releases)
- [Changelog](https://github.com/karma-runner/karma/blob/master/CHANGELOG.md)
- [Commits](karma-runner/karma@v1.4.1...v6.4.0)

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

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

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

Author: dependabot[bot]