GitHub Actions upload-pages-artifact bumped to v5

The CI pipeline's publish workflow now uses a newer version of the upload-pages-artifact action. This dependency bump brings the action in line with current practices — version 5 updated its underlying upload-artifact dependency to v7 and introduced an optional include-hidden-files toggle for deployments that need dotfile coverage. Keeping CI dependencies current reduces the risk of compatibility issues and ensures the workflow benefits from ongoing maintenance in the action itself.