Update gradle/actions action to v6

Author: renovate[bot]

.github/workflows/gradle.yml

@@ -24,7 +24,7 @@ jobs:
         distribution: 'zulu'
         java-version: 17
     - name: Setup Gradle
-      uses: gradle/actions/setup-gradle@v5
+      uses: gradle/actions/setup-gradle@v6
     - name: Run Gradle
       run: ./gradlew build
       env: