fix 逻辑取反

Src/Dlhis.ScheduledTask/TaskAssignment/Response/DeviceTaskAssignmentResponse.cs

@@ -84,7 +84,7 @@ public class DeviceTaskAssignmentResponse
     public string DeployPlace { get; set; }
 
     public int HeartbeatInterval { get; set; }
-    
+
     public DateTime LastHeartbeatTime { get; set; }
 
     public bool IsOffline
@@ -92,7 +92,7 @@ public class DeviceTaskAssignmentResponse
         get
         {
             if (HeartbeatInterval == 0) return false;
-            return LastHeartbeatTime.AddSeconds(HeartbeatInterval) > DateTime.Now;
+            return LastHeartbeatTime.AddSeconds(HeartbeatInterval) < DateTime.Now;
         }
     }
 }