Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/maven-publish.yml

@@ -16,7 +16,7 @@ jobs:
       packages: write
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up JDK 11
         uses: actions/setup-java@v5
         with:

.github/workflows/maven.yml

@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up JDK 17
         uses: actions/setup-java@v5
         with: