Upgrade to actions/checkout v4

Author: carlosame

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     name: Integration
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Setup JDK 8
         uses: actions/setup-java@v4