Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/maven-build.yml

@@ -21,7 +21,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup JDK
         uses: actions/setup-java@v5

.github/workflows/maven-deploy.yml

@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Configure GIT
         run: |