Bump karma-firefox-launcher from 2.1.1 to 2.1.2 (#151)

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
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -55,7 +55,7 @@
     "karma-chrome-launcher": "^3.1.0",
     "karma-coverage": "^2.0.3",
     "karma-coveralls": "^2.1.0",
-    "karma-firefox-launcher": "^2.1.1",
+    "karma-firefox-launcher": "^2.1.2",
     "karma-mocha": "^2.0.1",
     "karma-rollup-preprocessor": "^7.0.7",
     "karma-sourcemap-loader": "^0.3.8",