close tcp connection when restarting

src/main.rs

@@ -84,6 +84,7 @@ fn main() -> anyhow::Result<()> {
         println!("resetting modem ... ");
         println!("======================= MODEM =======================");
         let _ = mdm.start_sending(mqtt_username, mqtt_password).unwrap_or(());
+        let _ = mdm.tcp_close_connection().unwrap_or(());
         thread::sleep(Duration::from_millis(1500));
     }
 }