CI: use distro's Python for local deployment check

.github/workflows/CI.yml

@@ -69,6 +69,7 @@ jobs:
       - uses: actions/setup-python@v4
         with:
           python-version: '3.9'
+        if: matrix.os == 'ubuntu-20.04'
 
       # shallow clone for CI speed
       - name: Setup ansible extra vars in JSON file