Update actions/setup-python action to v6

Author: renovate[bot]

.github/workflows/tox_check.yaml

@@ -23,7 +23,7 @@ jobs:
           - windows-latest
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.env }}
       - name: Run image