Bump karma from 6.3.9 to 6.3.16 in /playground

Bumps [karma](https://github.com/karma-runner/karma) from 6.3.9 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@v6.3.9...v6.3.16)

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

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

Author: dependabot[bot]

playground/package-lock.json

@@ -30,7 +30,7 @@
     "@types/jasmine": "~3.8.0",
     "@types/node": "^12.11.1",
     "jasmine-core": "~3.8.0",
-    "karma": "~6.3.0",
+    "karma": "~6.3.16",
     "karma-chrome-launcher": "~3.1.0",
     "karma-coverage": "~2.0.3",
     "karma-jasmine": "~4.0.0",