Cross-compile for aarch64 on Linux

[mrexodia]

Reference: https://github.com/PyO3/setuptools-rust/blob/main/.github/workflows/ci.yml#L199

[williballenthin]

another example here (uses maturin, but i don't think thats strictly required):
https://github.com/williballenthin/lancelot/blob/d511a060aac86617a7ba50b62aee95ecea68f919/.github/workflows/publish-pypi.yaml