Ability to authenticate against specific index URLs #32
Description
Currently there is no authentication built-in in pypi-timemachine. As discovered in simple-repository/simple-repository#35, actually all you need to do is pass an appropriately configured authentication handler to the httpx client. We did this in simple-repository/simple-repository-server#20, but this won't apply automatically here since we are creating our own FastAPI app and http client. It would be easy to follow the same pattern as simple-repository-server, but I hope that we can improve the interfaces that the project provides to minimise the amount of setup that we need to do here in pypi-timemachine.
Tracking this here as I won't pick this off until there is a need, in the hope that in simple-repository-server things get streamlined further such that we don't need to worry about this here.