Bump karma-firefox-launcher from 2.1.1 to 2.1.2 (#491)

Bumps [karma-firefox-launcher](https://github.com/karma-runner/karma-firefox-launcher) from 2.1.1 to 2.1.2.
- [Release notes](https://github.com/karma-runner/karma-firefox-launcher/releases)
- [Changelog](https://github.com/karma-runner/karma-firefox-launcher/blob/master/CHANGELOG.md)
- [Commits](karma-runner/karma-firefox-launcher@v2.1.1...v2.1.2)

---
updated-dependencies:
- dependency-name: karma-firefox-launcher
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Matthijs van der Burgh <MatthijsBurgh@outlook.com>

Author: dependabot[bot]