Limit pack CI workflows to Python 3.10

[Copilot]

The GitHub Actions Build and Test / Python 3.8 job was failing during dependency bootstrap, before pack tests ran. The shared StackStorm CI workflow now inherits a pip pin from upstream st2 that is incompatible with Python 3.8 and 3.9.

• Workflow matrix

  • Override the reusable workflow input in both CI entrypoints to run only Python 3.10.
  • Applies to:
    • .github/workflows/build_and_test.yaml
    • .github/workflows/release.yaml

• Pack metadata

  • Bump pack.yaml version to 2.0.1.
  • Add a changelog entry documenting the CI matrix restriction so the metadata/version gate remains aligned with the workflow change.

• Effective change

  • CI now explicitly passes:

    with:
      enable-common-libs: true
      python-version: '["3.10"]'

This keeps the repository aligned with the current shared CI/bootstrap behavior without modifying the external workflow implementation.