Add support for Python 3.10

[hugovk]

Description of the desired feature

Related to fatiando/maintenance#15

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[hugovk]

Here's a WIP commit: https://github.com/hugovk/boule/commit/fd1c3af876327e519c4df7f4b19cdc071f35f915

Passes for Ubuntu and Windows, not for macOS:

https://github.com/hugovk/boule/actions/runs/1170845860

Errors like:

==================================== ERRORS ====================================
_ ERROR collecting .nox/test-3-10/lib/python3.10/site-packages/boule/__init__.py _
../lib/python3.10/site-packages/boule/__init__.py:10: in <module>
    from .ellipsoid import Ellipsoid
../lib/python3.10/site-packages/boule/ellipsoid.py:12: in <module>
    import numpy as np
../lib/python3.10/site-packages/numpy/__init__.py:391: in <module>
    raise RuntimeError(msg)
E   RuntimeError: Polyfit sanity test emitted a warning, most likely due to using a buggy Accelerate backend. If you compiled yourself, more information is available at numpy.org/doc/stable/user/building.html#accelerated-blas-lapack-libraries Otherwise report this to the vendor that provided NumPy.
E   RankWarning: Polyfit may be poorly conditioned

I expect this is caused by building NumPy from source, rather than using a precompiled binary wheel.

This is a downside of trying to test early during the release candidate, others dependencies may not be ready. Also building from source can be slow.

NumPy have created manylinux wheels for 3.10 but not macOS:

• https://github.com/numpy/numpy/issues/19630
• https://pypi.org/project/numpy/1.21.2/#files

Is anyone familiar with what's needed to build NumPy properly? Alternatively, macOS on 3.10 could be excluded for now, and rely on Linux/Windows on 3.10.

[leouieda]

Ouch. I suspect it's not worth the trouble to build numpy. Excluding Mac is reasonable. We may only need to build on Linux since there is little that can go wrong with numerical code nowadays between platforms (at least at this level of abstraction). We barely interact with the file system.

[leouieda]

Thanks for pushing this forward @hugovk! 💯

[hugovk]

Please see PR #87.