Check for proper method to close stream in asynchronous case

[daa]

Asynchronous httpcore streams do not have close() method, they provide aclose(). Fixes #1315 .

[daa]

To my mind such attribute checking is rather dubious because if stream must be closed then method to close it is part of its interface and thus all wrappers, mocks or substitutions must to implement it even if they are not required to be closed.

[florimondmanca]

Thanks!

[florimondmanca]

To my mind such attribute checking is rather dubious

I'd tend to agree yup, since the AsyncByteStream and SyncByteStream interface, documented here: https://www.encode.io/httpcore/api/, specify a .aclose() and .close() method respectively. Happy to consider removing this attribute checking as a follow-up!

[tomchristie]

Happily we'll be moving away from the stream .close() interface anyways.

Once we're treating HTTPTransport.request() as a context manager byte streams will just be either Iterable[byte] or AsyncIterable[byte]. (See #1274, encode/httpcore#145)

[daa]

Thank you very much!