Merge branch '7.2' into 7.3

* 7.2:
  Fix typo
  [VarExporter] Dump implicit-nullable types as explicit to prevent the corresponding deprecation
  Allow mixed root on CompoundConstraintTestCase validator
  [Serializer] Fix readonly property initialization from incorrect scope
  Update BrevoRequestParser.php

Author: nicolas-grekas

Test/CompoundConstraintTestCase.php

@@ -35,7 +35,7 @@ abstract class CompoundConstraintTestCase extends TestCase
     protected ValidatorInterface $validator;
     protected ?ConstraintViolationListInterface $violationList = null;
     protected ExecutionContextInterface $context;
-    protected string $root;
+    protected mixed $root;
 
     private mixed $validatedValue;