stdlib: add argument default values (#9501)

stdlib/sched.pyi

@@ -35,7 +35,7 @@ class scheduler:
     def enter(
         self, delay: float, priority: Any, action: _ActionCallback, argument: tuple[Any, ...] = ..., kwargs: dict[str, Any] = ...
     ) -> Event: ...
-    def run(self, blocking: bool = ...) -> float | None: ...
+    def run(self, blocking: bool = True) -> float | None: ...
     def cancel(self, event: Event) -> None: ...
     def empty(self) -> bool: ...
     @property