icon: update app icon

- GNOME 3.32 redesign of app icons.
  See Initiatives#2
  for more info.

fixes issue #6

/label ~"9. Initiative: AppIconRedesign"
1 job for wip/jimmac/app-icon-redesign in 2 minutes and 21 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #223418
build-and-test

00:02:21