minor #18779 [Serializer] Use NormalizerInterface instead of ObjectNormalizer (mtarld)

This PR was merged into the 6.3 branch.

Discussion
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[Serializer] Use `NormalizerInterface` instead of `ObjectNormalizer`

As mentioned in symfony/maker-bundle#1252 (comment), the documentation is telling to use a concrete implementation of the `NormalizerInteface`.
This is not the best in terms of OOP, and moreover doesn't work since Symfony 6.1 and the introduction of `TraceableNormalizer`.

Commits
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3e9af1b [Serializer] Use NormalizerInterface instead of ObjectNormalizer

Author: OskarStark

serializer/custom_normalizer.rst

@@ -48,6 +48,15 @@ to customize the normalized data. To do that, leverage the ``ObjectNormalizer``:
         }
     }
 
+.. deprecated:: 6.1
+
+    Injecting an ``ObjectNormalizer`` in your custom normalizer is deprecated
+    since Symfony 6.1. Implement the
+    :class:`Symfony\\Component\\Serializer\\Normalizer\\NormalizerAwareInterface`
+    and use the
+    :class:`Symfony\\Component\\Serializer\\Normalizer\\NormalizerAwareTrait` instead
+    to inject the ``$normalizer`` property.
+
 Registering it in your Application
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