Publish alpha(s) and nightly on https://anaconda.org/scientific-python-nightly-wheels/

Downstream users have requested wether we can do alpha to test new features (even if unstable).

I think we should also have nightly on [scientific Python anaconda index](https://anaconda.org/scientific-python-nightly-wheels/)

Start by reviewing the repository's existing release and package-publishing configuration, then trace how distribution artifacts are built and uploaded. Check whether the current workflow supports alpha and nightly channels, and define done as both being published to the scientific-python-nightly-wheels Anaconda index.

Written by the indexing model from the issue text.