fix: di injection

final 붙이지 않아서 빈 주입이 정상으로 이루어 지지 않은 부분 확인

Author: kss123456789

websocket-service/src/main/java/com/oneul_tanda/websocket_service/infrastructure/kafka/KafkaConsumerService.java

@@ -11,7 +11,7 @@
 @RequiredArgsConstructor
 public class KafkaConsumerService {
 
-    private WebSocketHandler webSocketHandler;
+    private final WebSocketHandler webSocketHandler;
 
     @KafkaListener(topics = KafkaTopics.WEBSOCKET_MESSAGE, groupId = "websocket_group")
     public void handleDeliveryStatusChanged(ReservationHeldEvent event) {