Upgrade to support XEP-0384: OMEMO Encryption 0.9.0 (2025-04-07) - #705

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