Allow specifying a minimum version

Description:
I've written a utility script in Python for some of our internal reusable workflows, and it depends on some features added in 3.13. Currently on ubuntu-latest 3.12 is the default version, but 3.13 is available in the tool cache. This means that I can add a setup-python step in my composite action that will activate 3.13. However at some point in the future, 3.13 will become the default, then 3.14, and etc etc. When 3.14 is the default, I'm fine using 3.14 for my script. However my action will continue to be pinned to 3.13, downgrading the version of Python.

It would be nice to specify a minimum version (in my case 3.13). If the default version is less than the minimum version, it would do as it does now and activate (or download if it's not in the tool cache) version 3.13. If the default version is 3.13 or greater, it would simply not do anything.

Justification:
Python is useful for writing small glue scripts in workflows where the full capabilities of python version management aren't required, but it would be nice to be able to automatically use this action to ensure a minimum version is present on the runner, to enable these glue scripts to run easily without a lot of effort on the person building the workflow.

Are you willing to submit a PR?
Given some guidance on the flow of the existing code, I could potentially be able to work on adding this functionality myself.

Start by tracing the setup-python step and its interaction with the runner's tool cache, focusing on how the default Python version is selected. Done means a minimum version can be requested, older defaults activate or download that version, and newer defaults are left unchanged; add coverage for both cases if the existing test flow supports it.