remove unused import.

src-tauri/src/pattern/frequency_shifting.rs

@@ -1,5 +1,5 @@
 use rand::Rng;
-use serde::{Deserialize, Serialize};
+use serde::Deserialize;
 use serde_repr::{Deserialize_repr, Serialize_repr};
 
 use crate::fraction::Fraction;