PR Summary

Resolves a problem identified by@ianhi in#22733 (comment) where just installing with

python -m pip install --upgrade --index-url https://pypi.anaconda.org/scipy-wheels-nightly/simple matplotlib

will fail because of dependencies not being present on the package index. This is expected, but isn't very clear if people have never had to deal with this before, and they could still run into issues like what PR#22751 addresses.

This PR adds the--pre flag to allow for a dev release to take precedence over a stable release and the--extra-index-url of normal PyPIhttps://pypi.org/simple to allow for matplotlib's dependencies to still get installed normally.

#22733 (comment) shows the install command working in a Python 3.10 Docker container.

PR Checklist

Tests and Styling

• Has pytest style unit tests (andpytest passes). (N/A)
• IsFlake 8 compliant (installflake8-docstrings and runflake8 --docstring-convention=all). (N/A)

Documentation

• New features are documented, with examples if plot related. (N/A)
• New features have an entry indoc/users/next_whats_new/ (follow instructions in README.rst there). (N/A)
• API changes documented indoc/api/next_api_changes/ (follow instructions in README.rst there). (N/A)
• Documentation is sphinx and numpydoc compliant (the docs shouldbuild without error). (N/A)