Resolve #3520495 "Drupal 11 compatibility"

Closes #3520495

src/EventSubscriber/JSComponentBuildEventSubscribe.php

@@ -14,7 +14,7 @@ class JSComponentBuildEventSubscribe implements EventSubscriberInterface {
   /**
    * {@inheritDoc}
    */
-  public static function getSubscribedEvents() {
+  public static function getSubscribedEvents(): array {
     return [
       Events::BUILD_COMPONENT_DATA => [
         ['buildJSComponentData'],