Bug 1889260 - Remove redundant import from mozprofile. r=webdriver-reviewers,whimboo

Differential Revision: https://phabricator.services.mozilla.com/D206438

testing/mozbase/rust/mozprofile/src/prefreader.rs

@@ -8,7 +8,6 @@ use std::borrow::Cow;
 use std::char;
 use std::error::Error;
 use std::io::{self, Write};
-use std::iter::Iterator;
 
 use std::str;
 use thiserror::Error;