Update actions/setup-python action to v6

Author: renovate[bot]

.github/workflows/build-website.yml

@@ -29,7 +29,7 @@ jobs:
           java-version: ${{ env.JDK_VERSION }}
           cache: gradle
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: 3.x
       - name: Set up Gradle