Bye bye Mambaforge and PyPy

[hmaarrfk]

Merge on new year's day, 2025!!!

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[hmaarrfk]

I might only be able to wait until https://en.wikipedia.org/wiki/Kiribati crosses into the new year ^_^....