credit method
Gets the current user's available credit.
Returns the available credit as an integer.
Implementation
Future<ApiResponseModel<int?>> credit() async {
final url = "$_baseUrl/user/credit";
final payload = {
'apiKey': _apiKey,
};
debugPrint("flutter_mon_sms_pro/user/credit/payload: $payload");
final r = await _dio.post(url, data: payload);
debugPrint("flutter_mon_sms_pro/user/credit/data: ${r.data}");
final response = ApiResponseModel.fromJson(
r.data,
(data) => data as int,
);
return response;
}