An HTTPCore transport that uses urllib3 as the HTTP networking backend. (This was initially shipped with HTTPX.)
When used with HTTPX, this transport makes it easier to transition from Requests to HTTPX by keeping the same underlying HTTP networking layer.
Compatible with: HTTPX 0.15.x, 0.16.x (i.e. HTTPCore 0.11.x and HTTPCore 0.12.x).
Note: not all urllib3 pool manager options are supported here — feel free to adapt this gist to your specific needs.