Update actions/checkout action to v6 (#40)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/maven-build.yml

@@ -12,7 +12,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Set up JDK 17
         uses: actions/setup-java@v4
         with:

.github/workflows/maven-pr.yml

@@ -8,7 +8,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Set up JDK 17
         uses: actions/setup-java@v4
         with:

.github/workflows/maven-release.yml

@@ -10,7 +10,7 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Generate changelog
         id: changelog