Switch to use oldest_supported_numpy for build-time requirements

[TylerADavis]

This should fix #1934 . pip install h5py is currently broken on arm64 Macs because h5py requests to build with an old version of NumPy that can't compile from source on arm64 Macs. While this has been fixed in NumPy 1.21 and 1.20, the devs say they will not be making another release of NumPy 1.19.

The NumPy devs I spoke with recommended oldest_supported_numpy, which lets us easily specify build-time requirements that are aware of platform specific requirements. I have tested this on my own arm64 Mac, and I can now build locally.

This PR moves the build time NumPy requirements out of SETUP_REQUIRES in setup.py and into the build-system requires in pyproject.toml. Based on the oldest_supported_numpy documentation, I believe this shouldn't cause issues even if h5py requests a newer version at runtime.

tox -e pre-commit and tox -e py39-test-deps both pass.

Closes #1836

[codecov]

Codecov Report

Merging #1993 (f09cabe) into master (dfb29a0) will not change coverage.
The diff coverage is n/a.

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  Files          17       17           
  Lines        2311     2311           
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  Hits         2078     2078           
  Misses        233      233           

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[NAThompson]

@TylerADavis : Could you also test this MR against python3.10?

[TylerADavis]

Sure, I just made a new Python 3.10 virtual environment, installed pkgconfig, and built h5py without issue.

tox -e py310-test-deps works as well

[aragilar]

I think sticking oldest-supported-numpy in SETUP_REQUIRES would allow H5PY_SETUP_REQUIRES to keep working for numpy.

[TylerADavis]

@aragilar You're saying to put oldest-supported-numpy into SETUP_REQUIRES, and then it'll get pulled into pyproject.toml anyways thanks to PEP 517?

[aragilar]

It won't get put into the contents of the file, but the idea would be it would be used for get_requires_for_build_wheel (we don't need the get_requires_for_build_sdist hook). I've filed an issue with setuptools to be able to set it at pypa/setuptools#2854 FYI.

[takluyver]

If we're going to use oldest-supported-numpy, I'm happy with just putting it in pyproject.toml as a static build dependency. If we do that, then we should have a single numpy >=1.14.5 in install_requires, so we don't have to duplicate the information from oldest-supported-numpy for runtime requirements.

[takluyver]

I've moved everything except mpi4py from setup_requires to the static list in pyproject.toml.

[takluyver]

Thanks @TylerADavis !