PHP8.4 Deprecated warning : Nullable types must be explicit

Problem/Motivation

Deprecated warning when clearing cache with php8.4 :
PHP Deprecated: Drupal\content_language_access\Form\ContentLanguageAccessAdminForm::buildForm(): Implicitly marking parameter $form_state as nullable is deprecated, the explicit nullable type must be used instead in /modules/contrib/content_language_access/src/Form/ContentLanguageAccessAdminForm.php on line 99

Proposed resolution

PHP 8.4: Implicitly nullable parameter declarations deprecated

Here is a patch against 2.x