minor symfony#20808 [Serializer] Update args (andreybolonin)

This PR was merged into the 6.4 branch.

Discussion
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[Serializer] Update args

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Commits
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b95b104 Update custom_normalizer.rst

Author: javiereguiluz

serializer/custom_normalizer.rst

@@ -33,9 +33,9 @@ to customize the normalized data. To do that, leverage the ``ObjectNormalizer``:
         ) {
         }
 
-        public function normalize($topic, ?string $format = null, array $context = []): array
+        public function normalize(mixed $object, ?string $format = null, array $context = []): array
         {
-            $data = $this->normalizer->normalize($topic, $format, $context);
+            $data = $this->normalizer->normalize($object, $format, $context);
 
             // Here, add, edit, or delete some data:
             $data['href']['self'] = $this->router->generate('topic_show', [