Bump karma from 2.0.4 to 6.3.16

Bumps [karma](https://github.com/karma-runner/karma) from 2.0.4 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@v2.0.4...v6.3.16)

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

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

package.json

@@ -40,7 +40,7 @@
     "eslint-plugin-html": "^4.0.5",
     "eslint-plugin-vue": "^4.5.0",
     "json-loader": "^0.5.4",
-    "karma": "^2.0.4",
+    "karma": "^6.3.16",
     "karma-chrome-launcher": "^2.0.0",
     "karma-cli": "^1.0.1",
     "karma-mocha": "^1.3.0",