Bump socket.io from 1.7.3 to 2.2.0

Bumps [socket.io](https://github.com/socketio/socket.io) from 1.7.3 to 2.2.0.
- [Release notes](https://github.com/socketio/socket.io/releases)
- [Commits](socketio/socket.io@1.7.3...2.2.0)

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

package.json

@@ -18,7 +18,7 @@
     "react-tap-event-plugin": "^2.0.1",
     "sequelize": "^5.8.7",
     "sha1": "^1.1.1",
-    "socket.io": "^1.7.3",
+    "socket.io": "^2.2.0",
     "uuid": "^3.0.1"
   },
   "boilerplate": {