Would be nice to have automated notice to implement what was laid out in APE 18 so we do not suddenly realize we have to do it and then drop a few old numpy versions all at once.

APE 18: https://github.com/astropy/astropy-APEs/blob/main/APE18.rst

tl;dr

Astropy core will support:

• All minor versions of Python released 42 months prior to a non-bugfix, and at minimum the two latest minor versions.
• All minor versions of numpy released in the 24 months prior to a non-bugfix, and at minimum the last three minor versions.
• Versions of other runtime dependencies released 24 months prior to a non-bugfix release.

xref astropy/astropy-APEs#80 and astropy/astropy-tools#177