Use char rather than &str as starts_with() argument

Author: samueltardieu

src/lib.rs

@@ -885,7 +885,8 @@ fn fill_todo(
             match dirs {
                 Ok(mut children) => {
                     if options.require_literal_leading_dot {
-                        children.retain(|x| !x.file_name().unwrap().to_str().unwrap().starts_with("."));
+                        children
+                            .retain(|x| !x.file_name().unwrap().to_str().unwrap().starts_with('.'));
                     }
                     children.sort_by(|p1, p2| p2.file_name().cmp(&p1.file_name()));
                     todo.extend(children.into_iter().map(|x| Ok((x, idx))));