Update gradle/actions action to v6

Author: renovate[bot]

.github/workflows/main-build.yml

@@ -20,7 +20,7 @@ jobs:
       - name: Checkout Repository
         uses: actions/checkout@v6
       - name: Validate Gradle Wrapper
-        uses: gradle/actions/wrapper-validation@v5
+        uses: gradle/actions/wrapper-validation@v6
       - name: Setup Java
         uses: actions/setup-java@v5
         with: