Update build system for new notarisation

[ktraunmueller]

Replace xcrun altool with xcrun notarytool, see https://developer.apple.com/documentation/security/notarizing_macos_software_before_distribution/customizing_the_notarization_workflow

https://successfulsoftware.net/2023/04/28/moving-from-altool-to-notarytool-for-mac-notarization/