Update macOS notifications to use UserNotifications framework

• Remove calls to deprecated NSUserNotification API
• Add calls for UserNotification framework

NOTES

• Applications need to be signed or they won't be able to have access to the notifications API. Sorry homebrew cask users and self-builders
• We can eventually add support for replying in-line from the notification and other fancy stuff now.

changed the description

Looks good to me :3

enabled an automatic merge when the pipeline for 912df292 succeeds

mentioned in commit a9dde2ef

merged