Fix grpc aio handler typing by XiaXia009 · Pull Request #15497 · python/typeshed

aio_handler = cast(grpc.aio.RpcMethodHandler[bytes, bytes], object())
aio_handler.unary_unary = cast(Callable[[bytes, grpc.aio.ServicerContext[bytes, bytes]], Awaitable[bytes]], None)
aio_handler.unary_stream = cast(Callable[[bytes, grpc.aio.ServicerContext[bytes, bytes]], AsyncIterator[bytes]], None)
aio_handler.stream_unary = cast(Callable[[AsyncIterator[bytes], grpc.aio.ServicerContext[bytes, bytes]], Awaitable[bytes]], None)
aio_handler.stream_stream = cast(
Callable[[AsyncIterator[bytes], grpc.aio.ServicerContext[bytes, bytes]], AsyncIterator[bytes]], None
)