Add Ukrainian language (lingodotdev#635)

Author: SeriyBg

i18n.json

@@ -13,7 +13,8 @@
       "it",
       "ar",
       "hi",
-      "pt-BR"
+      "pt-BR",
+      "uk-UA"
     ]
   },
   "buckets": {
@@ -24,4 +25,4 @@
     }
   },
   "$schema": "https://lingo.dev/schema/i18n.json"
-}
+}