Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/maven.yml

@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
+    - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6
     - name: Set up JDK 21
       uses: actions/setup-java@dded0888837ed1f317902acf8a20df0ad188d165 # v5
       with: