minor #58356 [Serializer] make data provider static (xabbuh)

This PR was merged into the 6.4 branch.

Discussion
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[Serializer] make data provider static

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        |
| License       | MIT

Commits
-------

06d3ab94c2 make data provider static

Author: xabbuh

Tests/Normalizer/Features/ContextMetadataTestTrait.php

@@ -77,7 +77,7 @@ public function testContextMetadataContextDenormalize(string $contextMetadataDum
         self::assertEquals('2011-07-28', $dummy->date->format('Y-m-d'), 'a specific denormalization context is used for this group');
     }
 
-    public function contextMetadataDummyProvider(): array
+    public static function contextMetadataDummyProvider(): array
     {
         return [
             [ContextMetadataDummy::class],