Log Message:
py-httpx: updated to 0.16.1

0.16.1

Fixed
* Support literal IPv6 addresses in URLs.
* Force lowercase headers in ASGI scope dictionaries.

0.16.0

Changed
* Preserve HTTP header casing.
* Drop `response.next()` and `response.anext()` methods in favour of \ 
`response.next_request` attribute.
* Closed clients now raise a runtime error if attempting to send a request.

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`.