Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/mvntest.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up JDK 17
         uses: actions/setup-java@v3
         with: