test(service): cover datetime interface support

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

tests/php/Unit/Service/FieldValueServiceTest.php

@@ -96,7 +96,7 @@ public function testUpsertPreservesImportedUpdatedAt(): void {
 			'finance',
 			'admin',
 			'users',
-			new \DateTime('2026-03-12T14:00:00+00:00'),
+			new \DateTimeImmutable('2026-03-12T14:00:00+00:00'),
 		);
 
 		$this->assertSame('2026-03-12T14:00:00+00:00', $stored->getUpdatedAt()->format(DATE_ATOM));