Remove unused import

Author: knutwalker

lib/src/graph.rs

@@ -20,7 +20,7 @@ use crate::{
     Operation,
 };
 use backoff::{Error, ExponentialBackoff};
-use std::{sync::Arc, time::Duration};
+use std::time::Duration;
 
 #[derive(Clone)]
 enum ConnectionPoolManager {