chore: re-vendor bitn.lua from lua-bitn v0.6.4 - #15

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, JohnnyMorganz/stylua-action@v4, leafo/gh-actions-lua@v11, leafo/gh-actions-luarocks@v5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Failed to save: <h2>Our services aren't available right now</h2><p>We're working to restore all services as soon as possible. Please check back soon.</p>0ZnqkagAAAAD+N0wrdmbrSrW/6GtHZsZJV1NURURHRTAzMTcARWRnZQ==

Failed to restore: Cache service responded with 400

gh-actions-lua: Storing into cache: lua:5.4.7:linux:x64: