Update actions/setup-python action to v6

Author: renovate[bot]

.github/workflows/docs.yml

@@ -25,7 +25,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Setup Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: '3.x'
           cache: 'pip'