This is partially a pex question but is there a way to force Pants/pex to resolve a dependency from a specific index? My use case is I have Airflow code that is deployed on Astronomer and their base docker image forces you to install any dependencies they have in their own Python index from that index. The problem is, sometimes their index is a few versions behind. I'm wondering if there's a way to only search that index when trying to generate the lockfile for certain dependencies. What I have currently is one requirements file that just pulls from PyPi and one with the header

-i <https://pip.astronomer.io/v2/>

that I want to pull from there, but pex does not seem to respect this in its lockfile generation, or at least not the way pants passes the requirements to pex.