警告去除

strategy/src/core.rs

@@ -7,7 +7,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::Duration;
 use chrono::{Utc};
 use rust_decimal::{Decimal};
-use rust_decimal::prelude::{ToPrimitive, Zero};
+use rust_decimal::prelude::{ToPrimitive};
 use rust_decimal_macros::dec;
 use tokio::spawn;
 use tokio::sync::mpsc::{Sender};