chore(deps): update actions/setup-python action to v6

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -25,7 +25,7 @@ jobs:
           - "3.12"
     steps:
       - uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: "${{matrix.python-version}}"
       - run: pip install tox