chore(be): 빠진 형변환 수정 (#285)

Author: flffkd12

backend/src/main/java/com/deliveranything/domain/order/service/CustomerOrderService.java

@@ -116,7 +116,7 @@ public CursorPageResponse<OrderResponse> getCompletedOrdersByCursor(
   ) {
     LocalDateTime lastCreatedAt = null;
     Long lastOrderId = null;
-    String[] decodedParts = CursorUtil.decode(nextPageToken);
+    String[] decodedParts = (String[]) CursorUtil.decode(nextPageToken);
 
     if (decodedParts != null && decodedParts.length == 2) {
       try {