Update actions/setup-python action to v6

Author: renovate[bot]

.github/workflows/publish-website.yaml

@@ -26,7 +26,7 @@ jobs:
           version: pre-release
 
       - name: Install python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: '3.13'
           cache: 'pip' # caching pip dependencies