Fix sliding window size for bidirectional Gemma 3 - #480

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

Application.get_env/3 is discouraged in the module body, use Application.compile_env/3 instead

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