GHA now uses Python 3.13

Author: cboulay

.github/workflows/build_cbsdk.yml

@@ -111,7 +111,7 @@ jobs:
         if: "!matrix.config.container"
         uses: actions/setup-python@v5
         with:
-          python-version: '3.12'
+          python-version: '3.13'
 
       - name: Install cibuildwheel
         if: "!matrix.config.container"