We do use pipenv. I like the idea of it, but I think we ran into issues with where the pipenv lives. We used to use `--system`, but that seemed buggy and/or idiosyncratic, so we started using a venv and then we started using PIPENV_VENV_IN_PROJECT=true (for some reason) and now it's causing other issues. It seems unclear how it's supposed to be used with Docker containers, but maybe we're just overcomplicating things?