Log Message:
py-httpcore: updated to 0.17.3

0.17.3 (5th July 2023)

- Support async cancellations, ensuring that the connection pool is left in a \ 
clean state when cancellations occur.
- The networking backend interface has [been added to the public \ 
API](https://www.encode.io/httpcore/network-backends). Some classes which were \ 
previously private implementation detail are now part of the top-level public \ 
API.
- Graceful handling of HTTP/2 GoAway frames, with requests being transparently \ 
retried on a new connection.
- Add exceptions when a synchronous `trace callback` is passed to an \ 
asynchronous request or an asynchronous `trace callback` is passed to a \ 
synchronous request.