ci: Set python-version

Author: bbhtt

.github/workflows/ci.yml

@@ -15,6 +15,9 @@ jobs:
       - uses: actions/checkout@v4
 
       - uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+          cache: 'pip'
 
       - name: Install dependencies
         run: pip install --user ruff