Add Serbian to languages [ci skip]
{ "code": "is", "name": "Icelandic" },
{ "code": "lt", "name": "Lithuanian" },
{ "code": "lv", "name": "Latvian" },
+ { "code": "rs", "name": "Serbian" },
{ "code": "sk", "name": "Slovak" },
{ "code": "sl", "name": "Slovenian" },
{
