Add type for headers array into CheckData.php

Author: leMaur

src/DataTransferObject/CheckData.php

@@ -9,6 +9,9 @@ final class CheckData
     public function __construct(
         public int $statusCode,
         public string $reasonPhrase,
+        /**
+         * @var string[][]
+         */
         public array $headers = [],
     ) {
     }