[Scheduler] Add MessageHandler result to the PostRunEvent

Author: alamirault

scheduler.rst

@@ -723,10 +723,15 @@ after a message is consumed::
         $schedule = $event->getSchedule();
         $context = $event->getMessageContext();
         $message = $event->getMessage();
+        $result = $event->getResult();
 
-        // do something with the schedule, context or message
+        // do something with the schedule, context, message or result
     }
 
+.. versionadded:: 7.3
+
+    The ``getResult()`` method was introduced in Symfony 7.3.
+
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