feat: upgrade phpunit to 12.5

tests/Service/BookingPriceCalculatorTest.php

@@ -28,7 +28,7 @@ class BookingPriceCalculatorTest extends TestCase
 
     protected function setUp(): void
     {
-        $eligibilityChecker = $this->createMock(ParticipantEligibilityChecker::class);
+        $eligibilityChecker = $this->createStub(ParticipantEligibilityChecker::class);
         $eligibilityChecker->method('isParticipantEligible')->willReturn(true);
 
         $this->roomPricingCalculator = new RoomPricingCalculator();