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

stdlib/sched.pyi

@@ -1,4 +1,4 @@
-from typing import Any, Callable, Dict, List, NamedTuple, Optional, Tuple
+from typing import Any, Callable, Dict, List, NamedTuple, Tuple
 
 class Event(NamedTuple):
     time: float
@@ -25,7 +25,7 @@ class scheduler:
         argument: Tuple[Any, ...] = ...,
         kwargs: Dict[str, Any] = ...,
     ) -> Event: ...
-    def run(self, blocking: bool = ...) -> Optional[float]: ...
+    def run(self, blocking: bool = ...) -> float | None: ...
     def cancel(self, event: Event) -> None: ...
     def empty(self) -> bool: ...
     @property