Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/gradle-build.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     if: "!contains(github.event.commits[0].message, '[ci-skip]')"
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: gradle/actions/wrapper-validation@v5
       - name: Set up JDK 17
         uses: actions/setup-java@v5

.github/workflows/publish.yml

@@ -10,7 +10,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5.0.1
+      - uses: actions/checkout@v6.0.2
       - uses: gradle/actions/wrapper-validation@v5
       - name: Set up JDK 17
         uses: actions/setup-java@v5.2.0
@@ -35,7 +35,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Downloading artifact
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - uses: thecodemonkey/action-get-gradle-version@master
         id: version
         with:
@@ -55,7 +55,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - uses: thecodemonkey/action-get-gradle-version@master
         id: version