Python 3.12

[carlwgeorge]

Hello, I'm the Fedora package maintainer for curio. Fedora Rawhide has updated to Python 3.12, which alerted me to the fact that curio doesn't build with Python 3.12. I was preparing some fixes for a pull request, but then noticed your contributing file. If you would like the fixes let me know and I'd be happy to submit them.

There are two issues that I can see.

multiprocessing.connection constants

ImportError while loading conftest '/home/carl/development/curio/tests/conftest.py'.
tests/conftest.py:4: in <module>
    from curio import Kernel
curio/__init__.py:6: in <module>
    from .queue import *
curio/queue.py:20: in <module>
    from . import workers
curio/workers.py:23: in <module>
    from .channel import Connection
curio/channel.py:31: in <module>
    CHALLENGE = mpc.CHALLENGE                   # b'#CHALLENGE#'
E   AttributeError: module 'multiprocessing.connection' has no attribute 'CHALLENGE'. Did you mean: '_CHALLENGE'?

CHALLENGE, WELCOME, and FAILURE were renamed to prefix them with an underscore. I realize this is likely an indication that the constants are private and should not be used, but importing the new private names does resolve the exception.

removed ssl.wrap_socket

ImportError while loading conftest '/home/carl/development/curio/tests/conftest.py'.
tests/conftest.py:4: in <module>
    from curio import Kernel
curio/__init__.py:12: in <module>
    from .network import *
curio/network.py:18: in <module>
    from . import ssl as curiossl
curio/ssl.py:30: in <module>
    @wraps(_ssl.wrap_socket)
E   AttributeError: module 'ssl' has no attribute 'wrap_socket'

ssl.wrap_socket has been deprecated since Python 3.7, and is removed outright in 3.12. The upstream notice recommends ssl.SSLContext.wrap_socket instead. Making that adjustment resolves the exception.

[hugovk]

Please see PR https://github.com/dabeaz/curio/pull/363 to apply these suggestions.