Big diff: Use new "|" union syntax (#5872)

stdlib/asyncio/exceptions.pyi

@@ -1,5 +1,4 @@
 import sys
-from typing import Optional
 
 if sys.version_info >= (3, 8):
     class CancelledError(BaseException): ...
@@ -7,9 +6,9 @@ if sys.version_info >= (3, 8):
     class InvalidStateError(Exception): ...
     class SendfileNotAvailableError(RuntimeError): ...
     class IncompleteReadError(EOFError):
-        expected: Optional[int]
+        expected: int | None
         partial: bytes
-        def __init__(self, partial: bytes, expected: Optional[int]) -> None: ...
+        def __init__(self, partial: bytes, expected: int | None) -> None: ...
     class LimitOverrunError(Exception):
         consumed: int
         def __init__(self, message: str, consumed: int) -> None: ...