🐛 Bug Report

When trying to use WorkbookReader as an async iterator with a for await of the TSC isn't recognizing the Symbol.asyncIterator property as defined.

Lib version: ^4.0.1

Steps To Reproduce

const workbookReader: IWorkbookReader = new exceljs.stream.xlsx.WorkbookReader(readStream, {});

 for await (const workbookSheet of workbookReader) {}

Exception: The WorkbookReader type must have a [Symbol.asyncIterator]() method which returns an asynchronous iterator.

The expected behaviour:

No errors should be triggered when using async iterators with an async loop.

Possible solution (optional, but very helpful):

Change the definition inside the index.d.ts line 1960 && 1974 like so:

[Symbol.asyncIterator](): AsyncGenerator<WorksheetReader>;

1. parentheses were missing.
2. Due to the implementation in JS code, it would be better to use AsyncGenerator instead of AsyncIterator Generics interfaces.

I could push a pull request if you wan't (and if i'm not wrong about all of this).
Thanks & have a good day.