Lightning Scheduler php 8.4 compatibility

Problem/Motivation

Module is not compatible with php 8.4

Steps to reproduce

Deprecated function: Drupal\lightning_scheduler\TransitionManager::__construct(): Implicitly marking parameter $translation as nullable is deprecated, the explicit nullable type must be used instead in include() (line 576 of /var/www/html/vendor/composer/ClassLoader.php)

Proposed resolution

Fix php code and make it compatible

Remaining tasks

Merge PR and make the new release.