syntax: update Unicode ages lookup

This was a missed fix for the Unicode 12.1 update.

Author: BurntSushi

src/unicode.rs

@@ -365,6 +365,8 @@ fn ages(canonical_age: &str) -> Result<AgeIter> {
         ("V9_0", age::V9_0),
         ("V10_0", age::V10_0),
         ("V11_0", age::V11_0),
+        ("V12_0", age::V12_0),
+        ("V12_1", age::V12_1),
     ];
     assert_eq!(AGES.len(), age::BY_NAME.len(), "ages are out of sync");