[EventDispatcher] fix @return type on EventSubscriberInterface

Author: nicolas-grekas

EventSubscriberInterface.php

@@ -43,7 +43,7 @@ interface EventSubscriberInterface
      * The code must not depend on runtime state as it will only be called at compile time.
      * All logic depending on runtime state must be put into the individual methods handling the events.
      *
-     * @return array<string, (string|list<string,int>|list<list<string,int>>)>
+     * @return array<string, string|array{0: string, 1: int}|list<array{0: string, 1?: int}>>
      */
     public static function getSubscribedEvents();
 }