Bump engine.io and karma

Bumps [engine.io](https://github.com/socketio/engine.io) to 6.2.1 and updates ancestor dependency [karma](https://github.com/karma-runner/karma). These dependencies need to be updated together.


Updates `engine.io` from 1.8.5 to 6.2.1
- [Release notes](https://github.com/socketio/engine.io/releases)
- [Changelog](https://github.com/socketio/engine.io/blob/main/CHANGELOG.md)
- [Commits](https://github.com/socketio/engine.io/compare/1.8.5...6.2.1)

Updates `karma` from 0.13.22 to 6.4.1
- [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/v0.13.22...v6.4.1)

---
updated-dependencies:
- dependency-name: engine.io
  dependency-type: indirect
- dependency-name: karma
  dependency-type: direct:development
...

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

package.json

@@ -30,7 +30,7 @@
     "grunt-string-replace": "1.3.1",
     "grunt-text-replace": "0.4.0",
     "jshint-stylish": "2.2.1",
-    "karma": "0.13.22",
+    "karma": "6.4.1",
     "karma-chrome-launcher": "3.1.0",
     "karma-coffee-preprocessor": "1.0.1",
     "karma-coverage": "2.0.3",