ci: use Gradle wrapper for release builds - #1302

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v3.3.0, actions/setup-java@v3.10.0, actions/upload-artifact@v4, gradle/gradle-build-action@v2.4.2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/