asyncio: updates for 3.11 (#7844)

CPython changes:

- https://github.com/python/cpython/commit/13c10bfb777483c7b02877aab029345a056b809c
- https://github.com/python/cpython/commit/9523c0d84f351a610dc651b234461eb015fa3b82
- https://github.com/python/cpython/commit/9f04ee569cebb8b4c6f04bea95d91a19c5403806
- https://github.com/python/cpython/commit/d03acd7270d66ddb8e987f9743405147ecc15087
- https://github.com/python/cpython/commit/195a46d6ffd4cec6c5fb69c5890f8b1758ac91ca

Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

stdlib/asyncio/timeouts.pyi

@@ -0,0 +1,19 @@
+from _typeshed import Self
+from types import TracebackType
+from typing_extensions import final
+
+__all__ = ("Timeout", "timeout", "timeout_at")
+
+@final
+class Timeout:
+    def __init__(self, when: float | None) -> None: ...
+    def when(self) -> float | None: ...
+    def reschedule(self, when: float | None) -> None: ...
+    def expired(self) -> bool: ...
+    async def __aenter__(self: Self) -> Self: ...
+    async def __aexit__(
+        self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
+    ) -> None: ...
+
+def timeout(delay: float | None) -> Timeout: ...
+def timeout_at(when: float | None) -> Timeout: ...