some minor clippy fixes

src/cargo-fmt/main.rs

@@ -387,8 +387,7 @@ fn get_targets_root_only(
                         .unwrap_or_default()
                         == current_dir_manifest
             })
-            .map(|p| p.targets)
+            .flat_map(|p| p.targets)
-            .flatten()
             .collect(),
     };
 

src/format_report_formatter.rs

@@ -20,6 +20,7 @@ impl<'a> FormatReportFormatterBuilder<'a> {
     }
 
     /// Enables colors and formatting in the output.
+    #[must_use]
     pub fn enable_colors(self, enable_colors: bool) -> Self {
         Self {
             enable_colors,

src/macros.rs

@@ -152,7 +152,7 @@ pub(crate) fn rewrite_macro(
 ) -> Option<String> {
     let should_skip = context
         .skip_context
-        .skip_macro(&context.snippet(mac.path.span).to_owned());
+        .skip_macro(context.snippet(mac.path.span));
     if should_skip {
         None
     } else {