Bump karma from 4.4.1 to 6.4.3

Bumps [karma](https://github.com/karma-runner/karma) from 4.4.1 to 6.4.3.
- [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...v6.4.3)

---
updated-dependencies:
- dependency-name: karma
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

package.json

@@ -38,7 +38,7 @@
     "jasmine-core": "^3.5.0",
     "jshint": "^2.13.6",
     "jshint-stylish": "^2.2.1",
-    "karma": "^4.4.1",
+    "karma": "^6.4.3",
     "karma-coverage": "^2.2.1",
     "karma-firefox-launcher": "^2.1.2",
     "karma-jasmine": "^1.0.2",