https://www.drupal.org/project/moon_phases/issues/3104603
Add the 'core_version_requirement' key in info.yml and composer.json files [#3104603] | Drupal.org
Jan 20, 2020 - Problem/Motivation Add core_version_requirement: ^8 || ^9 to admin_toolbar.info.yml to designate that the module is compatible with Drupal 9. See...