fix bug

mooctest-site-server/src/main/java/cn/iselab/mooctest/site/dao/AssignedTaskDao.java

@@ -17,8 +17,6 @@ import java.util.List;
 @Transactional
 public interface AssignedTaskDao extends PagingAndSortingRepository<AssignedTask, Long> {
 
-    List<AssignedTask> findByTaskIdAndParticipantId(long taskId, long participantId);
-
     List<AssignedTask> findByTaskIdAndWorkerId(long taskId, long workerId);
 
     List<AssignedTask> findByTaskId(long taskId);