Use python3 in build system information

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>

.github/workflows/test-windows.yml

@@ -41,7 +41,7 @@ jobs:
         cache-dependency-path: ".github/workflows/test-windows.yml"
 
     - name: Print build system information
-      run: python .github/workflows/system-info.py
+      run: python3 .github/workflows/system-info.py
 
     - name: python3 -m pip install wheel pytest pytest-cov pytest-timeout defusedxml
       run: python3 -m pip install wheel pytest pytest-cov pytest-timeout defusedxml