Use PEP 604 syntax wherever possible, part II (#7514)

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

stdlib/@python2/calendar.pyi

@@ -1,8 +1,8 @@
 import datetime
 from time import struct_time
-from typing import Any, Iterable, Optional, Sequence
+from typing import Any, Iterable, Sequence
 
-_LocaleType = tuple[Optional[str], Optional[str]]
+_LocaleType = tuple[str | None, str | None]
 
 class IllegalMonthError(ValueError):
     def __init__(self, month: int) -> None: ...