minor #5645 Add return type in EventListener (tourze)

This PR was merged into the 4.x branch.

Discussion
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Add return type in EventListener

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Commits
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149f5d5 Add return type in EventListener

src/Form/EventListener/CrudAutocompleteSubscriber.php

@@ -12,7 +12,7 @@
  */
 class CrudAutocompleteSubscriber implements EventSubscriberInterface
 {
-    public static function getSubscribedEvents()
+    public static function getSubscribedEvents(): array
     {
         return [
             FormEvents::PRE_SET_DATA => 'preSetData',