[BUG] csv write not work correct

## 🐛 Bug Report

exceljs 4.4.0

## Steps To Reproduce

```javascript
const ExcelJS = require('exceljs');
const fs = require('fs');

const workbook = new ExcelJS.Workbook();
const worksheet = workbook.addWorksheet('My Sheet');

const rows = [
[1, 'John Doe', new Date(1970, 1, 1)],
[2, 'Jane Doe', new Date(1965, 1, 7)],
[3, 'Sam Smith', new Date(1980, 5, 15)]
];
worksheet.addRows(rows);

const fileOptions = { sheetName: 'My Sheet' };

// Ensure the worksheet name is correct and exists
if (workbook.getWorksheet('My Sheet')) {
await workbook.csv.writeFile('output.csv', fileOptions)
.then(() => {
console.log('CSV 文件写入成功。');
})
.catch(error => {
console.error('写入 CSV 文件时出错:', error);
});
} else {
console.error('工作表名称 "My Sheet" 不存在。');
}

cannot write to 'My Sheet', open csv jsut get a output sheet, how to resolve?
```

## The expected behaviour:

## Possible solution (optional, but very helpful):

```javascript

```