Reduce dependencies to simplify bootstrapping

[tiran]

Fromager 0.30 depends on several Python packages with platform-specific extensions. Platlib wheels complicate bootstrapping of Fromager on a new platform or CPU architecture.

• charset_normalizer (dependency of `requests) has an optional extension module
• cryptography (dependency of PyGitHub) needs OpenSSL, Rust, cargo
• cffi (dependency of `cryptography) needs libffi, C compiler
• psutil needs C compiler
• pydantic-core needs Rust and maturin
• PyNaCl (dependency of PyGitHub) needs C compiler
• PyYAML has an optional extension module that can be disabled with PYYAML_FORCE_LIBYAML=0.
• wrapt (dependency of PyGitHub) needs C compiler

Some upstream projects (cryptography, PyNaCl, psutil, PyYAML) do not provide wheels for CPU archs like ppc64le and s390x. Cryptography is not going to provide them until upstream project has access to hardware for fast CI/CD.

We should try to reduce our dependency on platlib wheels to make bootstrapping easier. PyGitHub is a low hanging fruit. Fromager uses it to fetch a list of tags and tarball links from GH API. The feature can be re-implemented in a few lines of code.

[tiran]

In downstream we also depend on Twine. I submitted and landed a change that makes it possible to install Twine without keyring and cryptography, https://github.com/pypa/twine/issues/1158 . The change has not been released, yet.

[tiran]

469 has landed.