Use different interpreter_constraints for pants-plugins

[tachikoma-li]

First, thanks for the nice project!

We are developing Pants plugins in our project following the instruction here. It seems that we have to use Python 3.9 for pants-plugins. Is there way we can relax this constraint to use other versions of Python. E.g., in the CI we might want to use Python 3.12 for lint, but it doesn't seem to work with pants-plugins.

[benjyw]

Pants itself runs on Python 3.9 at the moment (there are plans afoot to bump this to at least 3.11). It bundles its own interpreter, so you don't need to worry about that. EXCEPT - as you've noticed - when you write plugins, because they must run under 3.9.

Pants does support multiple partitions of your codebase, each with different interpreter constraints, so that is probably the right way to do this?

[benjyw]

See https://www.pantsbuild.org/2.20/docs/python/overview/interpreter-compatibility#using-multiple-python-versions-in-the-same-project