Remove unused import.

wutil-rs/src/string.rs

@@ -7,7 +7,7 @@
 
 use std::{
     ffi::{c_char, c_int, CStr},
-    iter, mem, ptr, slice,
+    mem, ptr, slice,
 };
 
 use crate::memory::{alloc_bytes, alloc_string, ffi::wrealloc, free_bytes};