Issue #3471715 by TR: Drop D9 support

README.txt

@@ -12,7 +12,7 @@ which makes your site practically invite-only.
 
 INSTALLATION
 ------------
-https://www.drupal.org/docs/8/extending-drupal-8/installing-drupal-8-modules
+https://www.drupal.org/docs/extending-drupal/installing-modules
 
 CONFIGURATION
 -------------

regcode.info.yml

@@ -2,7 +2,7 @@ name: Registration codes
 type: module
 description: 'Provides functionality for using/enabling/requiring registration codes upon user registration.'
 package: Registration
-core_version_requirement: ^9.4 || ^10
+core_version_requirement: ^10.3 || ^11
 dependencies:
   - drupal:views