Update to actions/checkout 6.0.2

Author: jzheaux

.github/workflows/continuous-integration-workflow.yml

@@ -46,7 +46,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'spring-projects' }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: Set up gradle
         uses: spring-io/spring-gradle-build-action@v2
         with: