Remove an unneeded note

Author: javiereguiluz

components/serializer.rst

@@ -900,10 +900,6 @@ The Serializer component provides several built-in normalizers:
 :class:`Symfony\\Component\\Serializer\\Normalizer\\BackedEnumNormalizer`
     This normalizer converts a \BackedEnum objects into strings or integers.
 
-    .. note::
-
-        The PHP BackedEnum used by ``BackedEnumNormalizer`` requires at least PHP 8.1.
-
 :class:`Symfony\\Component\\Serializer\\Normalizer\\FormErrorNormalizer`
     This normalizer works with classes that implement
     :class:`Symfony\\Component\\Form\\FormInterface`.

serializer.rst

@@ -78,10 +78,6 @@ As well as the following normalizers:
 * :class:`Symfony\\Component\\Serializer\\Normalizer\\ProblemNormalizer`
 * :class:`Symfony\\Component\\Serializer\\Normalizer\\BackedEnumNormalizer`
 
-.. note::
-
-    The PHP BackedEnum used by ``BackedEnumNormalizer`` requires at least PHP 8.1.
-
 Other :ref:`built-in normalizers <component-serializer-normalizers>` and
 custom normalizers and/or encoders can also be loaded by tagging them as
 :ref:`serializer.normalizer <reference-dic-tags-serializer-normalizer>` and