Bump socket.io from 2.3.0 to 2.4.0

Bumps [socket.io](https://github.com/socketio/socket.io) from 2.3.0 to 2.4.0.
- [Release notes](https://github.com/socketio/socket.io/releases)
- [Changelog](https://github.com/socketio/socket.io/blob/2.4.0/CHANGELOG.md)
- [Commits](socketio/socket.io@2.3.0...2.4.0)

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

Author: dependabot[bot]

package-lock.json

@@ -9,7 +9,7 @@
   "author": "alpha74",
   "license": "ISC",
   "dependencies": {
-    "socket.io": "^2.3.0"
+    "socket.io": "^2.4.0"
   },
   "devDependencies": {
     "nodemon": "^2.0.2",