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

Localization authors:
- Marko Andrejić <marko.andrejic93@gmail.com>

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