fix callback

[Lu-Yi-Hsun]

when my iqoptionapi use last version websocket-client get this error

error from callback <bound method WebsocketClient.on_message of <iqoptionapi.ws.client.WebsocketClient object at 0x7f174fdb5e48>>: on_message() missing 1 required positional argument: 'message'
  File "/usr/lib/python3.7/site-packages/websocket/_app.py", line 343, in _callback
   callback(*args)

change the code
callback(*args)->callback(self, *args)
can fix my problem

[engn33r]

Follow-up comment: both the "if" and "else" branch result in the same callback(self, *args) call. This is how the code was before PR #442, which broke other functions and was partially reverted. I properly reverted this portion of the code with commit 3112b7d