What do you do when there is/are unavoidable package dependency conflict(s)? <-- biggest question in Python

Often times, split out into mutliple venvs.

For example, Sphinx requires py310+. My default is py39. myst-parser restricts dependencies rather than allow the latest and greatest. So there is an unavoidable need for two venv.

After setting up pyenv, how much setup is required, in pyproject.toml, to setup these two venv?

Looking at poetry, it's focused on one venv. And it's annoying it considers pyproject.toml to be a r/w file. I want to configure for an unlimited number of venv.