修复 Windows 下打开 Jupyter 报 NotImplementError

打开/c/Users/{USER_NAME}/AppData/Local/Programs/Python/Python38/Lib/asyncio/__init__/py.

修改

if sys.platform == 'win32':
    from .windows_event import *
    __all__ += windows_events.__all__

改为如下

import asyncio

if sys.platform == 'win32':
    from .windows_event import *
    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
    __all__ += windows_events.__all__