Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/main.yaml

@@ -16,7 +16,7 @@ jobs:
         java_version: [ 17, 21, 25 ]
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Set up JDK ${{ matrix.java_version }}
         uses: actions/setup-java@v4

.github/workflows/release.yaml

@@ -23,7 +23,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Set up JDK 17
         uses: actions/setup-java@v4

.github/workflows/snapshot_release.yaml

@@ -12,7 +12,7 @@ jobs:
   snapshot_release:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:

.github/workflows/update-versions-next-dev-iteration.yaml

@@ -21,7 +21,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0