Update gradle/actions action to v6

Author: renovate[bot]

.github/workflows/gradle-build.yml

@@ -10,7 +10,7 @@ jobs:
     if: "!contains(github.event.commits[0].message, '[ci-skip]')"
     steps:
     - uses: actions/checkout@v5
-    - uses: gradle/actions/wrapper-validation@v5
+    - uses: gradle/actions/wrapper-validation@v6
     - name: Set up JDK 21
       uses: actions/setup-java@v5
       with:

.github/workflows/publish.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v5
-      - uses: gradle/actions/wrapper-validation@v5
+      - uses: gradle/actions/wrapper-validation@v6
       - name: Set up JDK 21
         uses: actions/setup-java@v5
         with: