Bump engine.io and socket.io

Bumps [engine.io](https://github.com/socketio/engine.io) to 3.6.1 and updates ancestor dependency [socket.io](https://github.com/socketio/socket.io). These dependencies need to be updated together.


Updates `engine.io` from 3.4.0 to 3.6.1
- [Release notes](https://github.com/socketio/engine.io/releases)
- [Changelog](https://github.com/socketio/engine.io/blob/main/CHANGELOG.md)
- [Commits](socketio/engine.io@3.4.0...3.6.1)

Updates `socket.io` from 2.3.0 to 2.5.0
- [Release notes](https://github.com/socketio/socket.io/releases)
- [Changelog](https://github.com/socketio/socket.io/blob/main/CHANGELOG.md)
- [Commits](socketio/socket.io@2.3.0...2.5.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -71,7 +71,7 @@
     "redux": "^4.0.5",
     "redux-logger": "^3.0.6",
     "rethinkdbdash": "^2.3.31",
-    "socket.io": "^2.3.0",
+    "socket.io": "^2.5.0",
     "socket.io-client": "^2.3.1",
     "socketio-sticky-session": "^0.4.3",
     "spdy": "^4.0.2",