chore(deps): bump karma from 4.4.1 to 6.2.0 in /packages/stark-testing

Bumps [karma](https://github.com/karma-runner/karma) from 4.4.1 to 6.2.0.
- [Release notes](https://github.com/karma-runner/karma/releases)
- [Changelog](https://github.com/karma-runner/karma/blob/master/CHANGELOG.md)
- [Commits](karma-runner/karma@v4.4.1...v6.2.0)

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