Bump engine.io from 5.1.1 to 5.2.1

Bumps [engine.io](https://github.com/socketio/engine.io) from 5.1.1 to 5.2.1.
- [Release notes](https://github.com/socketio/engine.io/releases)
- [Changelog](https://github.com/socketio/engine.io/blob/5.2.1/CHANGELOG.md)
- [Commits](socketio/engine.io@5.1.1...5.2.1)

---
updated-dependencies:
- dependency-name: engine.io
  dependency-type: direct:production
...

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

Author: dependabot[bot]

package-lock.json

@@ -33,7 +33,7 @@
     "passport-http": "~0.3.0",
     "passport-local": "~1.0.0",
     "msgpack-js-browser": "~0.1.4",
-    "engine.io": "~5.1.1",
+    "engine.io": "~5.2.1",
     "engine.io-client": "~5.1.1",
     "amd-loader": "~0.0.8",
     "http-error": "~0.0.6",