[Breaking] Remove support for Python 3.7 & 3.8

[hallvictoria]

Issue describing the changes in this PR

3.7 & 3.8 builds are no longer part of the Python Worker nuget package, since they have been EOL for several years now. This will be starting host version 4.1046.

This change removes support for using 3.7 or 3.8 through Core Tools, so that customers who have those versions installed locally will need to update. This does not impact 3.9+ support.

// Using Python 3.8 -> not supported

// Using Python 3.14 -> no changes to experience

resolves #issue_for_this_pr

Pull request checklist

• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• My changes should not be added to the release notes for the next release
  • Otherwise: I've added my notes to release_notes.md
• I have added all required tests (Unit tests, E2E tests)

Additional information

Additional PR information

[liliankasem]

Going to hold this until at the very least v4.1046 of the host is being released with core tools.

But I am a little concerned about shipping a breaking change in a minor version, do we have telemetry about how many customers are still using this today? Would be nice to guage the impact here