Fix a typo making CI red

Author: HeahDude

serializer/custom_normalizer.rst

@@ -53,7 +53,7 @@ to customize the normalized data. To do that, leverage the ``ObjectNormalizer``:
     Injecting an ``ObjectNormalizer`` in your custom normalizer is deprecated
     since Symfony 6.4. Implement the
     :class:`Symfony\\Component\\Serializer\\Normalizer\\NormalizerAwareInterface`
-    and use the the
+    and use the
     :class:`Symfony\\Component\\Serializer\\Normalizer\\NormalizerAwareTrait` instead
     to inject the ``$normalizer`` property.