Update actions/checkout action to v7

Author: renovate[bot]

.github/workflows/tests.yml

@@ -13,7 +13,7 @@ jobs:
         os: [macos-14, macos-15, macos-26]
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - name: Install dependencies
         run: |
           python3 --version