[Validator] Add the type for ConstraintValidatorTestCase::createValidator

Author: stof

Tests/Validator/Constraints/UniqueEntityValidatorTest.php

@@ -131,7 +131,7 @@ protected function createEntityManagerMock($repositoryMock)
         return $em;
     }
 
-    protected function createValidator()
+    protected function createValidator(): UniqueEntityValidator
     {
         return new UniqueEntityValidator($this->registry);
     }