Bump karma from 5.0.9 to 6.4.3

Bumps [karma](https://github.com/karma-runner/karma) from 5.0.9 to 6.4.3.
- [Release notes](https://github.com/karma-runner/karma/releases)
- [Changelog](https://github.com/karma-runner/karma/blob/master/CHANGELOG.md)
- [Commits](karma-runner/karma@v5.0.9...v6.4.3)

---
updated-dependencies:
- dependency-name: karma
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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