Log Message:
py-httpcore: updated to 0.16.3

0.16.3
- Allow `ws` and `wss` schemes. Allows us to properly support websocket upgrade \ 
connections.
- Forwarding HTTP proxies use a connection-per-remote-host. Required by some \ 
proxy implementations.
- Don't raise `RuntimeError` when closing a connection pool with active \ 
connections. Removes some error cases when cancellations are used.
- Lazy import `anyio`, so that it's no longer a hard dependancy, and isn't \ 
imported if unused.