bug #45532 Fix deprecations on PHP 8.2 (nicolas-grekas)

This PR was merged into the 4.4 branch.

Discussion
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Fix deprecations on PHP 8.2

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | On the road to #44282
| License       | MIT
| Doc PR        | -

Commits
-------

ca566204d3 Fix deprecations on PHP 8.2

Tests/Normalizer/Features/ObjectDummy.php

@@ -2,6 +2,7 @@
 
 namespace Symfony\Component\Serializer\Tests\Normalizer\Features;
 
+#[\AllowDynamicProperties]
 class ObjectDummy
 {
     protected $foo;