Wrong f string in method `default_exception_handler` in events.py

Hello,

From version 6.8.0.2 to version 6.9.0 in the method `default_exception_handler` of `events.py` of the QtAsyncio module the following f string who uses double quotes everywhere has been introduced:

            print(f"{context["message"]} from task {context["task"]._name},"+
                    "read the following traceback:")

This is causing an error when using a QT applications with asyncio.

Sorry in advance if this issue is badly labelized or classified.

Best regards,

Jérémie