Bump docker/setup-buildx-action from 4.2.0 to 4.3.0 - #309

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. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/