Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/build.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: "ubuntu-latest"
     steps:
       - name: "Checkout Repository"
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name : "Validate Gradle Wrapper"
         uses: gradle/actions/wrapper-validation@v5
       - name: "Setup Java"