[Typing]: Correct typing for suppressing/forwarding contexts

[maxfischer2781]

There was a recent update to the typing spec that codified the meaning of return types for (async) contexts: -> bool/-> Literal[True] now mean the context may suppress exceptions, and any other annotations means exceptions are not suppressed. Notably, if a context does always return False in exit it should still not be -> bool to indicate the exception propagates.

At least one annotation is not correct with this scheme:

asyncstdlib/asyncstdlib/contextlib.py

Lines 202 to 204 in f9c80dd

	async def __aexit__(self, exc_type: Any, exc_val: Any, exc_tb: Any) -> bool:
	await self.thing.aclose()
	return False