Fix PHP 8.4 deprecation warnings

-Deprecated: Drupal\change_pwd_page\Form\ChangePasswordForm::buildForm(): Implicitly marking parameter $user as nullable is deprecated, the explicit nullable type must be used instead in /app/web/modules/contrib/change_pwd_page/src/Form/ChangePasswordForm.php on line 68

Resolved the above by explicitly marking $user as nullable with a "?"

src/Form/ChangePasswordForm.php

@@ -65,7 +65,7 @@ class ChangePasswordForm extends FormBase {
    * @param \Drupal\user\UserInterface $user
    *   The user object.
    */
-  public function buildForm(array $form, FormStateInterface $form_state, UserInterface $user = NULL) {
+  public function buildForm(array $form, FormStateInterface $form_state, ?UserInterface $user = NULL) {
     /** @var \Drupal\user\UserInterface $account */
     $this->userProfile = $account = $user;
     $user = $this->currentUser();