tombi: add build-tombi.yml for riscv64 wheels

[luhenry]

• Package: tombi
• Version: 1.4.1
• Source: https://github.com/tombi-toml/tombi
• Docs: https://github.com/tombi-toml/tombi

Compiles the tombi TOML formatter/linter/LSP CLI into a maturin bindings = "bin" wheel. Upstream publishes no riscv64 wheel.

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

Differs from upstream

• Patches the 0.0.0-dev placeholder version in pyproject.toml/Cargo.toml - upstream's release job does this via cargo xtask set-version from GITHUB_REF.

Testing

• No wheel-level test suite ships in the sdist beyond the __version__ check; drives lint/format against known-bad/messy TOML fixtures instead.

License: OK

Not rehearsed locally (riscv64 cross-toolchain); CI builds and tests on the real runner.