Add riscv64 (linux_riscv64) wheel to PyPI releases

Add linux_riscv64 wheel to PyPI releases

Summary

pip install httptools on riscv64 Linux currently requires building from source (~2 min on a 1.6 GHz RISC-V SoC). Adding linux_riscv64 to the wheel build matrix would give riscv64 users a prebuilt wheel.

Evidence

The wheel imports and passes basic smoke tests on riscv64 Linux.

Suggested CI change

Workflow: .github/workflows/release.yml

Add riscv64 to the matrix:

# In strategy.matrix.cibw_arch, add riscv64:
cibw_arch: [auto64, aarch64, universal2, riscv64]

# Add exclude for riscv64 on non-linux:
exclude:
  - os: windows-latest
    cibw_arch: riscv64
  - os: macos-latest
    cibw_arch: riscv64

QEMU action is already present (for aarch64).

Ecosystem context

• manylinux_2_28_riscv64 images are available on quay.io/pypa/ (landed in pypa/manylinux, 2025)
• cibuildwheel 3.x supports riscv64 via QEMU emulation
• auditwheel supports riscv64 platform tags
• maturin-action supports riscv64gc-unknown-linux-gnu cross-compilation
• Packages already shipping riscv64 wheels on PyPI: aiohttp, yarl, regex, markupsafe, charset-normalizer, rpds-py, multidict, propcache, watchfiles, rignore, setproctitle
• RISC-V hardware is shipping: SiFive HiFive, SpacemiT K1/K3, Sophgo SG2044 (64-core)

Our temporary index

While upstream support is pending, we maintain a PEP 503 index with 50+ riscv64 wheels for the Python ML/AI stack, built natively on RISC-V hardware.

Tracking repo: https://github.com/gounthar/riscv64-python-wheels

Bắt đầu với .github/workflows/release.yml và kiểm tra ma trận cibw_arch hiện có, các loại trừ nền tảng và thiết lập QEMU cho aarch64. Thêm hỗ trợ riscv64 như mô tả, sau đó xác minh rằng workflow phát hành tạo ra một wheel linux_riscv64 mà không bật nó trên Windows hoặc macOS.