refactor: reorganize imports and improve error message formatting

Reorganized imports in format_modifiers.rs to group related modules together for better code organization. Also improved error message formatting in test_date.rs by adding proper assertion formatting for macOS date setting error messages.

Author: mattsu2020

src/uu/date/src/format_modifiers.rs

@@ -33,8 +33,8 @@
 //! - `%^B`: Month name in uppercase (JUNE)
 //! - `%+4C`: Century with sign, padded to 4 characters (+019)
 
-use jiff::fmt::strtime::{BrokenDownTime, Config, PosixCustom};
 use jiff::Zoned;
+use jiff::fmt::strtime::{BrokenDownTime, Config, PosixCustom};
 use regex::Regex;
 use std::fmt;
 use std::sync::OnceLock;

tests/by-util/test_date.rs

@@ -481,9 +481,11 @@ fn test_date_set_mac_unavailable() {
         .arg("2020-03-11 21:45:00+08:00")
         .fails();
     result.no_stdout();
-    assert!(result
-        .stderr_str()
-        .starts_with("date: setting the date is not supported by macOS"));
+    assert!(
+        result
+            .stderr_str()
+            .starts_with("date: setting the date is not supported by macOS")
+    );
 }
 
 #[test]