Android: strip libnethack.so and bundle its debug symbols; bump to 3.6.7-4 - #5

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/upload-artifact@v5, android-actions/setup-android@v3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/