Use httpx in ClientWrapper

[noisecapella]

We should replace our current use of requests in ClientWrapper with httpx. We did this before but it was removed due to unexplained problems. However they say there is a 1.x release due this year so it may be a good time to give it a second try.

Currently, each HTTP request from requests blocks other async work, which can cause delays in Doof's responsiveness. Using httpx would help us prevent blocking communication