ci(si-2496): Migrate to shop/setup-python-action

[booniepepper]

ci(si-2496): Migrate to shop/setup-python-action

Hey there, we are mitigating #si-2496-remediation

We expect JavaScript and Python to migrate immediately based on this recent annoucement in #dev-up

This PR is a best-effort attempt to migrate for you!

• 💚 If this passes CI and we think it's a trivial change, we may merge this for you.
• 💔 If this doesn't pass CI or we think it's a non-trivial change, feel free to take over ownership, add commits to it, and do what it takes to merge it.
• ⚒️ If you have already mitigated it, or are working on it separately, feel free to close this PR with a comment referencing the other PR.

If you need help, reach out in #dev-up

[booniepepper]

Closing — this repo is public and cannot access shop/setup-python-action (internal org).