Update gradle/actions action to v6 (#966)

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

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -16,7 +16,7 @@ jobs:
           distribution: temurin
           java-version: 17
 
-      - uses: gradle/actions/setup-gradle@v4
+      - uses: gradle/actions/setup-gradle@v6
         with:
           gradle-version: 9.4.1
 
@@ -33,7 +33,7 @@ jobs:
           distribution: temurin
           java-version: 17
 
-      - uses: gradle/actions/setup-gradle@v4
+      - uses: gradle/actions/setup-gradle@v6
         with:
           gradle-version: 9.4.1