Version 0.16

[tomchristie]

0.16.0 (October 6th, 2020)

Changed

• Preserve HTTP header casing. (Pull Preserve header casing #1338, Preserve HTTP header casing httpcore#216, Preserve header casing. Take two. 🎬 python-hyper/h11#104)
• Drop response.next() and response.anext() methods in favour of response.next_request attribute. (Pull Drop .next()/.anext() in favour of response.next_request #1339)
• Closed clients now raise a runtime error if attempting to send a request. (Pull Tighten client closed-state behaviour #1346)

Added

• Add Python 3.9 to officially supported versions.
• Type annotate __enter__/__exit__/__aenter__/__aexit__ in a way that supports subclasses of Client and AsyncClient. (Pull Allow covariants of __enter__, __aenter__, and @classmethod #1336)