Bump actions/checkout from 4.2.2 to 7.0.0 - #4

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/setup-node@0a44ba7841725637a19e28fa30b79a866c81b0a6. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

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