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

stdlib/sunau.pyi

@@ -1,6 +1,6 @@
 import sys
 from _typeshed import Self
-from typing import IO, Any, NamedTuple, NoReturn, Optional, Union
+from typing import IO, Any, NamedTuple, NoReturn, Union
 
 _File = Union[str, IO[bytes]]
 
@@ -33,7 +33,7 @@ class Au_read:
     def __init__(self, f: _File) -> None: ...
     def __enter__(self: Self) -> Self: ...
     def __exit__(self, *args: Any) -> None: ...
-    def getfp(self) -> Optional[IO[bytes]]: ...
+    def getfp(self) -> IO[bytes] | None: ...
     def rewind(self) -> None: ...
     def close(self) -> None: ...
     def tell(self) -> int: ...
@@ -47,7 +47,7 @@ class Au_read:
     def getmarkers(self) -> None: ...
     def getmark(self, id: Any) -> NoReturn: ...
     def setpos(self, pos: int) -> None: ...
-    def readframes(self, nframes: int) -> Optional[bytes]: ...
+    def readframes(self, nframes: int) -> bytes | None: ...
 
 class Au_write:
     def __init__(self, f: _File) -> None: ...
@@ -73,7 +73,7 @@ class Au_write:
     def close(self) -> None: ...
 
 # Returns a Au_read if mode is rb and Au_write if mode is wb
-def open(f: _File, mode: Optional[str] = ...) -> Any: ...
+def open(f: _File, mode: str | None = ...) -> Any: ...
 
 if sys.version_info < (3, 9):
     openfp = open