PSA: Ubuntu GNOME packages development moved to Debian Salsa

[Marco Trevisan]

We finally moved all our git branches and tags for our GNOME desktop
packages to debian salsa.

So please don't push anything to launchpad git branches for any gnome
package (let me know if I missed any of them).

All the people in the desktop team, should be added to a salsa team, so
make sure you've an account there.

More informations on discourse: https://is.gd/asaMVw

Cheers