message: Export xlsx - added datetime format
diff: border: XlsxStyle.Default.Border,
  numberFormat: XlsxStyle.Default.NumberFormat,
  alignment: XlsxAlignment.Default);
  + var dateTimeStyle = XlsxStyle.Default.With(new XlsxNumberFormat($"yyyy-mm-dd hh:mm:ss"));
  // write header
  writer.SetDefaultStyle(headerStyle).BeginRow();
  for (var i = 0; i < reader.FieldCount; i++)
  - writer.Write(GetDaxColumnName(reader, i));
  + {
  + var daxColumnName = GetDaxColumnName(reader, i);
  + writer.Write(daxColumnName);
  + }
  // write data
  writer.SetDefaultStyle(XlsxStyle.Default);
  writer.Write(@decimal);
  break;
  case DateTime dateTime:
  - writer.Write(dateTime);
  + writer.Write(dateTime, dateTimeStyle);
  break;
  case string @string:
  writer.Write(@string);
  