fix rustfmt due to the ast change

src/tools/rustfmt/src/imports.rs

@@ -458,7 +458,7 @@ impl UseTree {
                     version,
                 });
             }
-            UseTreeKind::Nested(ref list) => {
+            UseTreeKind::Nested { items: ref list, .. } => {
                 // Extract comments between nested use items.
                 // This needs to be done before sorting use items.
                 let items = itemize_list(