Determine Python version from a series of questions

[blakeNaccarato]

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Description

Support 3.10 on up by default, eventually clamping to minimum supported Python as 3.9 EOLs. The question series goes as follows:

• Modify Python versions?
• Support 3.10?
• Support 3.11?
  ...
• Which version will the development environment use? (pre-filled from the lowest supported version above)

And so on. The composed Jinja variable will be derived from that and can directly populate GitHub Actions matrices without unwieldy fromJson semantics in a dependent Action. Python versions aren't changed all that often anyways, but a single source of truth is preferable.