Add support for socketio/socket.io-redis-adapter onmessage Handler

[kinseyost]

https://github.com/socketio/socket.io-redis-adapter/blob/main/lib/index.ts#L215 The current parser blows up when socket.io-redis-atapter tries to call parser.decode (it doesn't exist on this parser)

Here you go :)

[darrachequesne]

Hi! This parser is not meant to be used with the adapter, you can simply use:

import { createAdapter } from '@socket.io/redis-adapter';

io.adapter(createAdapter(pubClient, subClient, {
  parser: {
    decode(msg) {
      return JSON.parse(msg);
    },
    encode(msg) {
      return JSON.stringify(msg);
    },
  },
}));