Update actions/checkout action to v7

Author: renovate[bot]

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
         python-version: ["3.11", "3.12", "3.13"]
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v5