Watch `manylinux2014` (PEP 599) to publish aarch64 wheels on pypi

[Hywan]

For the moment, we can't publish our aarch64 binary wheels onto pypi because it breaks the manylinux2010 policy. However, it seems that manylinux2014 could solve this. Discussion happens here, pypa/manylinux#84. Something we should track.

For the moment, wheels are attached to Github releases as assets. See the example of the 1.0.0 release: https://github.com/wasmerio/wasmer-python/releases/tag/1.0.0.

[bennuttall]

numpy is releasing manylinux2014_aarch64 wheels now which work on Raspberry Pi with an aarch64 OS: https://pypi.org/project/numpy/#files

[messense]

You can pass --manylinux 2014 to maturin build to make it create manylinux2014 wheel. It won't be necessary after PyO3/maturin#424 released.