pyfaup-rs: add build-pyfaup-rs.yml for riscv64 wheels

[luhenry]

• Package: pyfaup-rs
• Version: 0.4.19
• Source: https://github.com/ail-project/faup-rs
• Docs: https://github.com/ail-project/faup-rs

Compiles the PyO3 bindings for faup-rs, a zero-allocation URL parser. Upstream publishes no riscv64 wheel.

Mirrors the linux job of upstream's maturin.yml.

Differs from upstream

• Drop musllinux - rustup ships no riscv64 musl target.
• Install Rust toolchain in-container via rustup - cibuildwheel provides none.
• Copy LICENSE beside python/pyproject.toml before build - maturin globs licence files relative to the pyproject directory, so upstream's own wheel ships none.

Testing

• same as upstream

License: Package is GPL-3.0; upstream's own wheel ships no licence text, so the build adds it.

Built on cp312; 5 passed, 0 skipped.