uvloop fails on 3.14

[graingert]

ImportError while loading conftest '/home/runner/work/anyio/anyio/tests/conftest.py'.
tests/conftest.py:17: in <module>
    import uvloop
/opt/hostedtoolcache/Python/3.14.0-alpha.1/x64/lib/python3.14/site-packages/uvloop/__init__.py:9: in <module>
    from .loop import Loop as __BaseLoop  # NOQA
uvloop/includes/stdlib.pxi:47: in init uvloop.loop
    ???
E   AttributeError: module 'asyncio' has no attribute 'AbstractChildWatcher'

[fantix]

Ah, this has been deprecated since Python 3.12 and will be removed in 3.14. Let's get rid of it in uvloop too.