Bump actions/setup-python from 5 to 6 (#569)

Author: dependabot[bot]

.github/workflows/tests.yml

@@ -30,7 +30,7 @@ jobs:
       - uses: actions/checkout@v5
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}