WSOD due to 'core' key set

Problem/Motivation

Loading the site results in the error message:

The website encountered an unexpected error. Please try again later.

More info is in https://www.drupal.org/files/issues/2023-09-14/at_tools-8.x-3.5-err.txt

This is only a problem for Drupal core 9 or 10; the debug info says, in part, "The 'core_version_requirement' constraint (^9 || ^10) requires the 'core' key not be set in modules/contrib/at_tools/at_theme_generator/at_theme_generator.info.yml ..."

Steps to reproduce

Install at_tools 8.x-3.5 and the theme generator.

Proposed resolution

Remove the line below

core: 8.x

from both of these files:
/at_tools/at_tools.info.yml
/at_tools/at_theme_generator/at_theme_generator.info.yml

Remaining tasks

The above fixes the problem; what remains is to incorporate the fix into the module, with testing, etc. The fix is simple, though.