Replacement for Rackspace for staging built wheels

[peterjc]

See See https://mail.python.org/pipermail/scipy-dev/2020-February/023990.html and https://github.com/matthew-brett/multibuild/issues/304

There are quite a few project's using the multibuild system now, no clear consensus as yet for where to host the built wheels. Committing them to a github repository (using a deployment key) might be a workable solution...

[peterjc]

I am inclined to use https://anaconda.org/multibuild-wheels-staging/ and will get in touch with Matti as per https://mail.python.org/pipermail/numpy-discussion/2020-August/080924.html and his reply.

[peterjc]

Matti Picus has kindly given me access to https://anaconda.org/multibuild-wheels-staging/settings/access (under anaconda account peterjc), and as instructed I defined $BIOPYTHON_STAGING_UPLOAD_TOKEN with initial permissions "Allow all operations on PyPI repositories", but had to also add read/write API access.

We now have the TravisCI built wheels for Linux and macOS uploaded to anaconda:

https://anaconda.org/multibuild-wheels-staging/biopython/files

AppVeyor update for the Windows wheels pending. See notes on #7.

(So far this is deliberately just rebuilding the most recent release)

[peterjc]

Just noticed while scanning the AppVeyor logs, that it automatically caches "build artefacts" like wheels for 6 months, e.g.

https://ci.appveyor.com/project/biopython/biopython-wheels/builds/34931909/job/kob16cx8ejl3ui4u/artifacts

So we don't actually need to stage them somewhere central. However, that does mean far less manual point and click to collect the wheels ready for uploading to PyPI, and having them on anaconda allows easy direct install from there too.

[peterjc]

Closed by #7, although it looks like the AppVeyor Python 3.8 builds are currently broken with the release of setuptools v50.0.0