chore: update actions/checkout action to v4

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.github/workflows/ci.yaml

@@ -23,7 +23,7 @@ jobs:
     if: ${{ !startsWith(github.head_ref, 'renovate/') || !startsWith(github.head_ref, 'renovate/') }}
     steps:
       - name: checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Unshallow
         run: |
           git fetch --prune --unshallow