Update actions/setup-python action to v6

Author: renovate[bot]

.github/workflows/tests.yaml

@@ -15,7 +15,7 @@ jobs:
     steps:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
       - name: Lint with ruff