chore(deps): update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/tests.yml

@@ -26,7 +26,7 @@ jobs:
 
     steps:
       - name: Check out the repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Set up Python ${{ matrix.python-version }}
         uses: actions/setup-python@v3