fix unused-must-use (#2490)

unused-must-use

install/src/command.rs

@@ -507,7 +507,7 @@ fn add_to_path(new_path: &str) -> bool {
                         Ok(())
                     }
                     append_file(&rcfile, &shell_export_string).unwrap_or_else(|err| {
-                        format!("Unable to append to {rcfile:?}: {err}");
+                        println!("Unable to append to {rcfile:?}: {err}");
                     });
                     modified_rcfiles = true;
                 }