Update HeartbeatAlarmReceiver.java

app/src/main/java/com/nbee/echolink/broadcast/HeartbeatAlarmReceiver.java

@@ -33,10 +33,11 @@ public class HeartbeatAlarmReceiver extends BroadcastReceiver {
      */
     @Override
     public void onReceive(Context context, Intent intent) {
+        thisContext = context;
         // 执行发送心跳信号的逻辑
         sendHeartbeatSignal();
         // 在发送心跳后，重新设置下一次心跳发送的时间
-        MonitorService.scheduleHeartbeat(context);
+        MonitorService.scheduleHeartbeat(thisContext);
     }