Use Final in pyexpat module (#12541)

stdlib/pyexpat/model.pyi

@@ -1,11 +1,13 @@
-XML_CTYPE_ANY: int
-XML_CTYPE_CHOICE: int
-XML_CTYPE_EMPTY: int
-XML_CTYPE_MIXED: int
-XML_CTYPE_NAME: int
-XML_CTYPE_SEQ: int
+from typing import Final
 
-XML_CQUANT_NONE: int
-XML_CQUANT_OPT: int
-XML_CQUANT_PLUS: int
-XML_CQUANT_REP: int
+XML_CTYPE_ANY: Final = 2
+XML_CTYPE_EMPTY: Final = 1
+XML_CTYPE_MIXED: Final = 3
+XML_CTYPE_NAME: Final = 4
+XML_CTYPE_CHOICE: Final = 5
+XML_CTYPE_SEQ: Final = 6
+
+XML_CQUANT_NONE: Final = 0
+XML_CQUANT_OPT: Final = 1
+XML_CQUANT_REP: Final = 2
+XML_CQUANT_PLUS: Final = 3