LINGUAS: Add ru

For some reason this wasn't done automatically on this branch, so do it
manually.
6 jobs for gnome-3-30 in 16 minutes and 54 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #138357
flatpak:app

00:10:00

 
  Test
passed #138358
flatpak:tests

00:03:20

 
  Review
passed #138359
review

00:00:26

manual #138360
allowed to fail manual
stop_review
 
  Cross Distro
passed #138361
fedora:29

00:03:00

passed #138362
ubuntu:devel

00:03:06