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

Author: renovate[bot]

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out repo
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Set up Python
         uses: actions/setup-python@v3
       - name: Run pre-commit
@@ -28,7 +28,7 @@ jobs:
       - uses: actions/setup-python@v3
         with:
           python-version: ${{ matrix.python-version }}
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Test with tox
         run: |
           pip install tox