Missed an unwrap in the README.md example

Author: nekevss

README.md

@@ -21,7 +21,7 @@ let iso8601_date = PlainDate::try_new(2025, 3, 3, Calendar::default()).unwrap();
 // Create a new date with the japanese calendar
 let japanese_date = iso8601_date.with_calendar(Calendar::from_str("japanese").unwrap()).unwrap();
 assert_eq!(japanese_date.era(), Some(tinystr!(16, "reiwa")));
-assert_eq!(japanese_date.era_year().unwrap(), Some(7));
+assert_eq!(japanese_date.era_year(), Some(7));
 assert_eq!(japanese_date.month().unwrap(), 3)
 ```