PyPy wheels and moving off rackspace

[mattip]

As per matthew-brett/multibuild#304, projects should not upload to rackspace since this is no longer free. Over at numpy-wheels, we chose to use anaconda.org for staging and weekly builds. Cython chose to upload them to github as release packages. One advantage to using a shared location is that any of the wheels in that location can be installed with a single -i https://pypi.anaconda.org/scipy-wheels-nightly/simple argument to pip.

If you choose the anaconda route, I can give an admin rights to the anaconda staging areas, and help you do something like the numpy-wheels upload code.

If you choose the github route, here is what cython did to upload there

In any case, it would be nice to provide PyPy wheels for linux64, macOS, win32 and aarch64, which is now pretty simple to do with multibuild (update to latest devel HEAD) and travis (for everything except windows)

[mattsplats]

I know some work has been done recently to move the main repo to Azure pipelines, but I would argue for sticking with multibuild and migrating to Anaconda so that the additional arch wheels can be provided through this repo.

pywavelets did this recently: MacPython/pywavelets-wheels#13