app row: Add shadow to app icons

The new GNOME application icons require shadows when placed on a
light background.

See Initiatives#2

Fixes #573
1 job for <span class="ref-name">add-shadows-to-icons</span> in 15 minutes and 49 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #243252
build-gnome-software

00:15:49