ci: bump actions/checkout from 4.4.0 to 7.0.1 - #10

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: docker/build-push-action@10e90e3645eae34f1e60eeb005ba3a3d33f178e8, docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f, docker/setup-qemu-action@c7c53464625b32c7a7e944ae62b3e17d2b600130. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/