Resolve #3490037 "Min drupal 10.3"

Closes #3490037

src/Plugin/Block/PrivateMessageActionsBlock.php

 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\private_message\Plugin\Block;
 
 use Drupal\Core\Access\AccessResult;
@@ -39,7 +41,7 @@ class PrivateMessageActionsBlock extends BlockBase implements ContainerFactoryPl
   /**
    * {@inheritdoc}
    */
-  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition): PrivateMessageActionsBlock {
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition): self {
     return new static(
       $configuration,
       $plugin_id,
@@ -60,7 +62,7 @@ class PrivateMessageActionsBlock extends BlockBase implements ContainerFactoryPl
   /**
    * {@inheritdoc}
    */
-  public function build() {
+  public function build(): array {
     if (!$this->currentUser->hasPermission('use private messaging system')) {
       return [];
     }