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

module/Core/src/Visit/Model/UnknownVisitLocation.php

@@ -25,14 +25,7 @@ final class UnknownVisitLocation implements VisitLocationInterface
         return 'Unknown';
     }
 
-    /**
-     * Specify data which should be serialized to JSON
-     * @link https://php.net/manual/en/jsonserializable.jsonserialize.php
-     * @return mixed data which can be serialized by <b>json_encode</b>,
-     * which is a value of any type other than a resource.
-     * @since 5.4.0
-     */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         return [
             'countryCode' => 'Unknown',