CI: Python 3.8 and 3.9 not found on macOS

[PhilippPlank]

Describe the bug
Python 3.8 and 3.9 on macOS no longer work, and actions complains about them not being a real version.

To reproduce current behavior
Run a CI test.

2. I get this error ...
   Version 3.8 was not found in the local cache
   Error: Version 3.8 with arch arm64 not found
   The list of all available versions can be found here: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json

Expected behavior
CI test does not fail.

Environment (please complete the following information):

• Device: GitHub runner
• OS: MacOS
• Lava version: NA

Additional context
macos-latest now uses M1 runners (macos-14-arm64) and 3.9 and earlier aren't available anymore. CI should stick to stick to macos-12 or macos-13 for now, to fix this issue.