处理警告

standard/tests/exchange_test.rs

@@ -1,13 +1,10 @@
 use std::collections::{BTreeMap};
 use std::{env};
-use std::fs::File;
-use toml::from_str;
-use std::io::{Error, Read};
+use std::io::{Error};
 use std::sync::Arc;
 use std::sync::atomic::AtomicBool;
 use std::time::Duration;
 use rust_decimal_macros::dec;
-use serde::Deserialize;
 use tokio::sync::mpsc::{channel, Receiver, Sender};
 use tokio::try_join;
 use tracing::{error, trace};