Use ASGI event types from Uvicorn

[Masynchin]

As for now, starlette/types.py offers such types for ASGI events:

starlette/starlette/types.py

Lines 10 to 11 in 07427f8

	Scope = typing.MutableMapping[str, typing.Any]
	Message = typing.MutableMapping[str, typing.Any]

Unlike the rich types from uvicorn/_types.py:

https://github.com/encode/uvicorn/blob/5bf788f0eb0fc771f5c4eed8f282c7ec256565d2/uvicorn/_types.py#L68-L82

Is it a good idea to port this types from uvicorn here?

[Kludex]

There were some attempts to do that before. It's too much work... But you are welcome to create a PR.

[Masynchin]

There were some attempts to do that before. It's too much work... But you are welcome to create a PR.

I decided that I do not give enough time for the implementation, but can provide a little more to the conversation. Can we use your library for the types, like the optional dependency, and fallback to the current ones when it is not installed?