Update workflow actions to remove warning messages

[GuyHoozdis]

When GitHub Actions runs the test.yml workflow file a user warning is raised. One for each platform version combination in the matrix.

Updating the checkout action and setup-python action resolve the issue.

• Checkout: https://github.com/marketplace/actions/checkout
• setup-python: https://github.com/marketplace/actions/setup-python

[GuyHoozdis]

I looked for any instructions for contributors, but didn't find any. If I overlooked, please point it out to me. Thanks.

[di]

Open/closing to kickstart CI.

[di]

Thanks!