Bump actions/checkout from 2 to 4 (#901)

Author: dependabot[bot]

.github/workflows/maven.yml

@@ -19,7 +19,7 @@ jobs:
         java: ["17"]
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Set up JDK ${{ matrix.java }}
         uses: actions/setup-java@v2
         with: