Update gradle/actions action to v6 (#146)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/gradle-wrapper-validation.yml

@@ -13,4 +13,4 @@ jobs:
         with:
           fetch-depth: 1
           show-progress: false
-      - uses: gradle/actions/wrapper-validation@v5
+      - uses: gradle/actions/wrapper-validation@v6