Resolves #5544

This adds official support for the upcoming Python 3.12 release in a couple of days to the metadata of Streamlink's sdists/bdists.
https://peps.python.org/pep-0693/

cffi 1.16.0 has finally been released yesterday with support for py312, which means we can finally label Streamlink as py312 compatible and remove the custom-built wheel:
https://github.com/python-cffi/cffi/releases/tag/v1.16.0

cffi is a transitive dependency on Windows via trio, and it's optionally required (without declaring it as a dependency) by pycryptodome:

• https://github.com/python-trio/trio/blob/v0.22.2/setup.py#L93
• https://github.com/Legrandin/pycryptodome/blob/v3.19.0/lib/Crypto/Util/_raw_api.py#L85