Pontoon: Update Sinhala (si) localization of AMO Frontend
Pontoon: Update Sinhala (si) localization of AMO Frontend

Co-authored-by: හෙළබස සමූහය (HelaBasa Group) <b9ffe367efdf35a5e502b4e19d7d8d74a75e4ac7@yalu.lk>

mozilla/addons-frontend,mozilla/addons-frontend,mozilla/addons-frontend,mozilla/addons-frontend