ci: when testing, install python 3.12, required by zephyr now

Zephyr now requires python 3.12, so install this version when testing
the SDK.

Signed-off-by: Anas Nashif <[email protected]>

Author: nashif

.github/workflows/ci.yml

@@ -1310,12 +1310,11 @@ jobs:
 
     steps:
     - name: Set up Python
-      if: ${{ runner.os == 'Windows' }}
       uses: actions/setup-python@v5
       with:
-        # Force Python 3.10 because the twister is not compatible with a Python
-        # version lower than 3.8 on Windows.
-        python-version: '3.10'
+        # Force Python 3.12, which is the minimum Python version supported by
+        # Zephyr and intended to be used with Zephyr SDK.
+        python-version: '3.12'
 
     - name: Set up test environment (Linux)
       if: ${{ runner.os == 'Linux' }}