Import Debian changes 0.7.9-1ubuntu1

libnotify (0.7.9-1ubuntu1) focal; urgency=medium
.
  * Merge with Debian, remaining changes
  * debian/control.in,
    debian/rules:
    - generate the notification-daemon recommends with some hacks,
      this allows notification-daemon to be demoted to universe
  * Also make autopkgtest dependencies cross-test-friendly.