Update actions/checkout action to v4

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

Author: renovate[bot]

.github/workflows/ci.yml

@@ -14,4 +14,4 @@ jobs:
 
     steps:
       - name: Check out code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4