Bump karma-firefox-launcher from 2.1.0 to 2.1.2

Bumps [karma-firefox-launcher](https://github.com/karma-runner/karma-firefox-launcher) from 2.1.0 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@v2.1.0...v2.1.2)

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

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Author: dependabot[bot]