shellcheck-py: add build-shellcheck-py.yml for riscv64 wheels

[luhenry]

• Package: shellcheck-py
• Version: 0.11.0.1
• Source: https://github.com/ryanrhee/shellcheck-py
• Docs: https://github.com/ryanrhee/shellcheck-py

Downloads and repackages the prebuilt shellcheck binary from koalaman/shellcheck's GitHub releases into a platform-tagged wheel; nothing is compiled. Upstream publishes no riscv64 wheel, though setup.cfg already carries a riscv64 download entry for the shellcheck binary itself (koalaman/shellcheck v0.11.0 ships one).

Mirrors upstream's own pip wheel --no-deps --wheel-dir wheels . build, driven inside the manylinux_2_39_riscv64 image so the wheel gets a manylinux tag.

Differs from upstream

• Forces --plat-name=manylinux_2_39_riscv64 on setup.py bdist_wheel - upstream's own CI never builds a tagged Linux wheel itself (only Windows/macOS get wheel-tags: true).

Testing

• same as upstream (shellcheck --version, shellcheck --help)

License: OK