Avoid feature name 'checked_duration_since' in a Tidy test

Author: vi

src/tools/tidy/src/features/tests.rs

@@ -2,8 +2,8 @@ use super::*;
 
 #[test]
 fn test_find_attr_val() {
-    let s = r#"#[unstable(feature = "checked_duration_since", issue = "58402")]"#;
-    assert_eq!(find_attr_val(s, "feature"), Some("checked_duration_since"));
+    let s = r#"#[unstable(feature = "tidy_test_never_used_anywhere_else", issue = "58402")]"#;
+    assert_eq!(find_attr_val(s, "feature"), Some("tidy_test_never_used_anywhere_else"));
     assert_eq!(find_attr_val(s, "issue"), Some("58402"));
     assert_eq!(find_attr_val(s, "since"), None);
 }