Bump karma from 6.3.13 to 6.3.15 (#4824)

Bumps [karma](https://github.com/karma-runner/karma) from 6.3.13 to 6.3.15.
- [Release notes](https://github.com/karma-runner/karma/releases)
- [Changelog](https://github.com/karma-runner/karma/blob/master/CHANGELOG.md)
- [Commits](https://github.com/karma-runner/karma/compare/v6.3.13...v6.3.15)

---
updated-dependencies:
- dependency-name: karma
  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

@@ -35,7 +35,7 @@
     "istanbul-instrumenter-loader": "^3.0.1",
     "jasmine-core": "4.0.0",
     "jsdoc": "^3.3.2",
-    "karma": "6.3.13",
+    "karma": "6.3.15",
     "karma-chrome-launcher": "3.1.0",
     "karma-cli": "2.0.0",
     "karma-coverage": "2.1.1",