minor symfony#53114 [Serializer] Move dummy to fixtures folder (HypeMC)

This PR was merged into the 5.4 branch.

Discussion
----------

[Serializer] Move dummy to fixtures folder

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | -
| License       | MIT

Commits
-------

d07e44c [Serializer] Moves dummy to fixtures folder

Author: nicolas-grekas

src/Symfony/Component/Serializer/Tests/Php80Dummy.php renamed to src/Symfony/Component/Serializer/Tests/Fixtures/Php80Dummy.php

@@ -9,7 +9,7 @@
  * file that was distributed with this source code.
  */
 
-namespace Symfony\Component\Serializer\Tests;
+namespace Symfony\Component\Serializer\Tests\Fixtures;
 
 final class Php80Dummy
 {

src/Symfony/Component/Serializer/Tests/Normalizer/ObjectNormalizerTest.php

@@ -39,6 +39,7 @@
 use Symfony\Component\Serializer\Tests\Fixtures\OtherSerializedNameDummy;
 use Symfony\Component\Serializer\Tests\Fixtures\Php74Dummy;
 use Symfony\Component\Serializer\Tests\Fixtures\Php74DummyPrivate;
+use Symfony\Component\Serializer\Tests\Fixtures\Php80Dummy;
 use Symfony\Component\Serializer\Tests\Fixtures\SiblingHolder;
 use Symfony\Component\Serializer\Tests\Normalizer\Features\AttributesTestTrait;
 use Symfony\Component\Serializer\Tests\Normalizer\Features\CacheableObjectAttributesTestTrait;
@@ -56,7 +57,6 @@
 use Symfony\Component\Serializer\Tests\Normalizer\Features\TypedPropertiesObject;
 use Symfony\Component\Serializer\Tests\Normalizer\Features\TypedPropertiesObjectWithGetters;
 use Symfony\Component\Serializer\Tests\Normalizer\Features\TypeEnforcementTestTrait;
-use Symfony\Component\Serializer\Tests\Php80Dummy;
 
 /**
  * @author Kévin Dunglas <[email protected]>