Fix reactor stop hang

[EliaOnceAgain]

Twisted reactor not exiting cleanly. Encountered while running pytest, which does not exit after all tests are finished. Reproduction steps below.

Ubuntu 22.04.1 LTS
Python 3.10.6
binance-connector==1.18.0
Twisted==22.8.0
pytest==7.2.0

From: Invoking Twisted From Other Threads

Methods within Twisted may only be invoked from the reactor thread unless otherwise noted... This means that if you start a thread and call a Twisted method, you might get correct behavior… or you might get hangs, crashes, or corrupted data. So don’t do it.

Test case:

import pytest
from binance.spot import Spot
from binance.websocket.spot.websocket_client import SpotWebsocketClient as WebsocketClient


class TestBinanceAPI:
    @pytest.fixture(scope="class")
    def ws_client(self):
        client = WebsocketClient()
        client.start()
        yield client
        client.stop()

    def test_hello_world(self, ws_client):
        assert ws_client

Expected outcome:
Test finishes successfully, pytest exists gracefully at the end.

Actual outcome:
Test finishes successfully, pytest hangs indefinitely

Pre fix output

> /my-path/tests/test_wsclient.py(12)ws_client()
-> client.stop()
> /my-venv/lib/python3.10/site-packages/binance/websocket/websocket_client.py(15)stop()
-> reactor.stop()

(Pdb) ll
 10         def stop(self):
 11             try:
 12                 self.close()
 13             finally:
 14                 import pdb; pdb.set_trace()
 15  ->            reactor.stop()
(Pdb) reactor._stopped
False
(Pdb) reactor.running
True
(Pdb) n
--Return--
> /my-env/lib/python3.10/site-packages/binance/websocket/websocket_client.py(15)stop()->None
-> reactor.stop()
(Pdb) reactor.running
True <<<<<<< Still true
(Pdb) reactor._stopped
True <<<<<<< Changed to true, yet still running
(Pdb) continue

At this point, pytest hangs, never exits or gives up control of the command line. Last printed logline:
============================================================================= 1 passed in 124.56s (0:02:04) ==============================================================================

Post fix output

-> reactor.callFromThread(reactor.stop)
(Pdb) ll
 10         def stop(self):
 11             try:
 12                 self.close()
 13             finally:
 14                 import pdb; pdb.set_trace()
 15                 # reactor.stop()
 16  ->             reactor.callFromThread(reactor.stop)
(Pdb) reactor._stopped
False
(Pdb) reactor.running
True
(Pdb) n
--Return--
> /my-env/lib/python3.10/site-packages/binance/websocket/websocket_client.py(16)stop()->None
-> reactor.callFromThread(reactor.stop)
(Pdb) reactor._stopped
True
(Pdb) reactor.running
False <<<<< correctly changed
(Pdb) continue

At this point, pytest finishes successfully, exits gracefully, and returns command line control to the caller.