Fix Consent entity and integration test

Entity fix:
- Make 'attribute' column nullable: true so doctrine:schema:create
  generates a nullable column. CI uses schema:create, not migrations.
  storeConsentHash only sets attribute_stable, not attribute, causing
  SQLSTATE 1364 without this fix.

Test fix:
- Rename class EngineBlock_Corto_Model_Consent_Integration_Test to
  ConsentIntegrationTest to match filename (PHPUnit warning)
- Make consentTypeProvider() static (PHPUnit deprecation)

Author: kayjoosten

src/OpenConext/EngineBlockBundle/Authentication/Entity/Consent.php

@@ -55,7 +55,7 @@ class Consent
     /**
      * @var string
      */
-    #[ORM\Column(type: \Doctrine\DBAL\Types\Types::STRING, length: 80)]
+    #[ORM\Column(type: \Doctrine\DBAL\Types\Types::STRING, length: 80, nullable: true)]
     public ?string $attribute = null;
 
     /**

tests/library/EngineBlock/Test/Corto/Model/ConsentIntegrationTest.php

@@ -26,7 +26,7 @@
 use OpenConext\EngineBlockBundle\Authentication\Repository\DbalConsentRepository;
 use PHPUnit\Framework\TestCase;
 
-class EngineBlock_Corto_Model_Consent_Integration_Test extends TestCase
+class ConsentIntegrationTest extends TestCase
 {
     use MockeryPHPUnitIntegration;
 
@@ -235,7 +235,7 @@ public function test_upgrade_to_stable_consent_not_applied_when_stable($consentT
         $this->assertNull($this->consent->upgradeAttributeHashFor($serviceProvider, $consentType));
     }
 
-    public function consentTypeProvider()
+    public static function consentTypeProvider(): iterable
     {
         yield [ConsentType::TYPE_IMPLICIT];
         yield [ConsentType::TYPE_EXPLICIT];