Update actions/setup-python action to v6

Author: renovate[bot]

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - name: Setup Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
       - name: Install dependencies