Update loop task factory typing with kwargs

For `PY311` the task factory will be called with the context kwarg. This
is not correctly reflected in the typing for `Loop.set_task_factory` and
`Loop.get_task_factory`. This commit addresses this with a protocol.
Since `uvloop` requires a minimum Python 3.8 version, in which
`typing.Protocol` is available; the more appropriate `typing.Unpack` for
kwargs is introduced in Python 3.11.

uvloop/loop.pyi

@@ -11,6 +11,7 @@ from typing import (
     Generator,
     List,
     Optional,
+    Protocol,
     Sequence,
     Tuple,
     TypeVar,
@@ -24,6 +25,14 @@ _ExceptionHandler = Callable[[asyncio.AbstractEventLoop, _Context], Any]
 _SSLContext = Union[bool, None, ssl.SSLContext]
 _ProtocolT = TypeVar("_ProtocolT", bound=asyncio.BaseProtocol)
 
+
+class TaskFactoryCallable(Protocol):
+    def __call__(
+        self, loop: asyncio.AbstractEventLoop, coro: Generator[Any, None, _T], **kwargs: Any
+    ) -> asyncio.Future[_T]:
+        ...
+
+
 class Loop:
     def call_soon(
         self, callback: Callable[..., Any], *args: Any, context: Optional[Any] = ...
@@ -52,17 +61,8 @@ class Loop:
         *,
         name: Optional[str] = ...,
     ) -> asyncio.Task[_T]: ...
-    def set_task_factory(
-        self,
-        factory: Optional[
-            Callable[[asyncio.AbstractEventLoop, Generator[Any, None, _T]], asyncio.Future[_T]]
-        ],
-    ) -> None: ...
-    def get_task_factory(
-        self,
-    ) -> Optional[
-        Callable[[asyncio.AbstractEventLoop, Generator[Any, None, _T]], asyncio.Future[_T]]
-    ]: ...
+    def set_task_factory(self, factory: Optional[TaskFactoryCallable]) -> None: ...
+    def get_task_factory(self) -> Optional[TaskFactoryCallable]: ...
     @overload
     def run_until_complete(self, future: Generator[Any, None, _T]) -> _T: ...
     @overload