add asyncio debug handler

[ajmirsky]

when a client tries to connect the broker but it is refused due to certificate error, there is no message on the broker side. turn this exception into a logger

import asyncio

def custom_exception_handler(loop, context):
    print("🚨 Asyncio error:", context["message"])
    if "exception" in context:
        print("Exception:", context["exception"])

loop = asyncio.get_event_loop()
loop.set_exception_handler(custom_exception_handler)


asyncio.get_event_loop().set_debug(True)