Bump karma-browserstack-launcher from 1.4.0 to 1.6.0

Bumps [karma-browserstack-launcher](https://github.com/karma-runner/karma-browserstack-launcher) from 1.4.0 to 1.6.0.
- [Release notes](https://github.com/karma-runner/karma-browserstack-launcher/releases)
- [Changelog](https://github.com/karma-runner/karma-browserstack-launcher/blob/master/CHANGELOG.md)
- [Commits](karma-runner/karma-browserstack-launcher@v1.4.0...v1.6.0)

---
updated-dependencies:
- dependency-name: karma-browserstack-launcher
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]