Fix some tests

Author: dunglas

src/Graphql/Serializer/ItemNormalizer.php

@@ -47,7 +47,7 @@ public function normalize($object, $format = null, array $context = [])
     /**
      * {@inheritdoc}
      */
-    protected function normalizeCollectionOfRelations(PropertyMetadata $propertyMetadata, iterable $attributeValue, string $resourceClass, string $format = null, array $context): array
+    protected function normalizeCollectionOfRelations(PropertyMetadata $propertyMetadata, $attributeValue, string $resourceClass, string $format = null, array $context): array
     {
         // to-many are handled directly by the GraphQL resolver
         return [];

src/Serializer/AbstractItemNormalizer.php

@@ -435,10 +435,9 @@ protected function getAttributeValue($object, $attribute, $format = null, array
     /**
      * Normalizes a collection of relations (to-many).
      *
-     * @param object      $relatedObject
-     * @param string|null $format
+     * @param iterable $attributeValue
      */
-    protected function normalizeCollectionOfRelations(PropertyMetadata $propertyMetadata, iterable $attributeValue, string $resourceClass, string $format = null, array $context): array
+    protected function normalizeCollectionOfRelations(PropertyMetadata $propertyMetadata, $attributeValue, string $resourceClass, string $format = null, array $context): array
     {
         $value = [];
         foreach ($attributeValue as $index => $obj) {