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

Author: renovate[bot]

.github/workflows/ci.yml

@@ -31,7 +31,7 @@ jobs:
         uses: actions/checkout@v5
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
           cache: pip