Bump karma from 5.1.1 to 6.3.16 (#357)

Bumps [karma](https://github.com/karma-runner/karma) from 5.1.1 to 6.3.16.
- [Release notes](https://github.com/karma-runner/karma/releases)
- [Changelog](https://github.com/karma-runner/karma/blob/master/CHANGELOG.md)
- [Commits](karma-runner/karma@v5.1.1...v6.3.16)

---
updated-dependencies:
- dependency-name: karma
  dependency-type: direct:development
...

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

package.json

@@ -69,7 +69,7 @@
     "grunt-mocha-test": "^0.13.3",
     "grunt-webpack": "^3.1.3",
     "istanbul": "github:kpdecker/istanbul",
-    "karma": "^5.1.1",
+    "karma": "^6.3.16",
     "karma-chrome-launcher": "^3.1.0",
     "karma-mocha": "^2.0.1",
     "karma-mocha-reporter": "^2.0.0",