PHP 8.4 compatibility issues

Problem/Motivation

The following issues show up when using php 8.4:

PHP Deprecated:  Drupal\group_content_menu\GroupContentMenuParentFormSelector::parentSelectElement(): Implicitly marking parameter $menus as nullable is deprecated, the explicit nullable type must be used instead in /var/www/html/docroot/modules/contrib/group_content_menu/src/GroupContentMenuParentFormSelector.php on line 53

PHP Deprecated:  Drupal\group_content_menu\GroupContentMenuParentFormSelector::getMenuOptions(): Implicitly marking parameter $menu_names as nullable is deprecated, the explicit nullable type must be used instead in /var/www/html/docroot/modules/contrib/group_content_menu/src/GroupContentMenuParentFormSelector.php on line 77

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes