GraalPy support

[kurtmckee]

What's the problem this feature will solve?

The GitHub action actions/setup-python has recently merged a PR to support GraalPy (note that this support hasn't been released yet -- to access it, I think it's still necessary to reference actions/setup-python@main in a CI workflow).

GraalPy will be the third interpreter type available when running jobs in GitHub CI, and I'd like to have a way to test it alongside CPython and PyPy, as a defined tox environment.

Describe the solution you'd like

I'd like to be able to specify GraalPy as a target interpreter for a tox environment.

Their version scheme appears to differ from CPython and PyPy -- in GitHub it's referenced as "graalpy-23.0"...it seems they currently target Python 3.10 as the language version.

Alternative Solutions

I haven't tried anything to resolve this. I imagine (but haven't tested!) that manipulating the $PATH might allow tox to only see the GraalPy python executable.

Additional context

[gaborbernat]

This sounds like something that should live as a plugin first until gets wide adoption.