Merge pull request silverstripe#353 from creative-commoners/pulls/5/p…

…hp84

API Explicity mark nullable parameters for PHP 8.4

tests/php/Tasks/GorriecoeMigrationTaskTest.php

@@ -319,7 +319,7 @@ public static function provideMigrateHasManyRelations(): array
     #[DataProvider('provideMigrateHasManyRelations')]
     public function testMigrateHasManyRelations(
         array $hasManyConfig,
-        string $ownerFixture = null,
+        ?string $ownerFixture = null,
         array $addColumns = []
     ): void {
         GorriecoeMigrationTask::config()->set('has_many_links_data', $hasManyConfig);