fix(elasticsearch): change normalize return type to compatible with other normalizers (#6493)

Author: Koenstell

src/Elasticsearch/Serializer/ItemNormalizer.php

@@ -88,7 +88,7 @@ public function supportsDenormalization(mixed $data, string $type, ?string $form
     /**
      * {@inheritdoc}
      */
-    public function normalize(mixed $object, ?string $format = null, array $context = []): array
+    public function normalize(mixed $object, ?string $format = null, array $context = []): \ArrayObject|array|string|int|float|bool|null
     {
         return $this->decorated->normalize($object, $format, $context);
     }