Update actions/checkout action to v4 (#2241)

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

.github/workflows/flyway-dupe-checker.yml

@@ -13,6 +13,6 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Check for duplicate Flyway scripts
         run: ./bin/ci/flyway-dupe-checker.sh