fix:修复固定速度模式计算下一个执行时间bug（毫秒超出int范围）

xxl-job-admin/src/main/java/com/xxl/job/admin/core/thread/JobScheduleHelper.java

@@ -372,7 +372,7 @@ public class JobScheduleHelper {
             Date nextValidTime = new CronExpression(jobInfo.getScheduleConf()).getNextValidTimeAfter(fromTime);
             return nextValidTime;
         } else if (ScheduleTypeEnum.FIX_RATE == scheduleTypeEnum /*|| ScheduleTypeEnum.FIX_DELAY == scheduleTypeEnum*/) {
-            return new Date(fromTime.getTime() + Integer.valueOf(jobInfo.getScheduleConf())*1000 );
+            return new Date(fromTime.getTime() + Long.parseLong(jobInfo.getScheduleConf()) * 1000L);
         }
         return null;
     }