Pontoon: Update Serbian (sr) localization of Firefox Screenshots
Pontoon: Update Serbian (sr) localization of Firefox Screenshots

Localization authors:
- Марко Костић (Marko Kostić) <marko.m.kostic@gmail.com>

mozilla-services/pageshot,mozilla-services/screenshots,mozilla-services/screenshots,mozilla-services/pageshot,mozilla-services/pageshot,mozilla-services/pageshot,mozilla-services/screenshots,mozilla-services/screenshots