Added package to delegate the execution of event listeners to a swoole task worker

module/Core/src/EventDispatcher/ShortUrlVisited.php

@@ -3,7 +3,9 @@ declare(strict_types=1);
 
 namespace Shlinkio\Shlink\Core\EventDispatcher;
 
-final class ShortUrlVisited
+use JsonSerializable;
+
+final class ShortUrlVisited implements JsonSerializable
 {
     /** @var string */
     private $visitId;
@@ -17,4 +19,9 @@ final class ShortUrlVisited
     {
         return $this->visitId;
     }
+
+    public function jsonSerialize(): array
+    {
+        return ['visitId' => $this->visitId];
+    }
 }