🐛 Bug Report

Lib version: exceljs@4.3.0

Steps To Reproduce

1. Prepare an xlsx file such that the first sheet contains a rowBreaks(page break).
2. Watch rowBreaks right after loading the file.

const reader1 = new FileReader();
reader1.readAsArrayBuffer("theRowBreaked1.xlsx")
    .then(xlsxArrayBuffer1 => {
        const workbook1 = new ExcelJS.Workbook();
        return workbook1.xlsx.load(xlsxArrayBuffer1 as ArrayBuffer);
   }).then(workbook2 => {
          console.log( workbook2.worksheets[0].rowBreaks);  // empty !!
});

The expected behaviour:

I expected workbook1.worksheets[0].rowBreaks to expect page break positions in the xlsx file.
But workbook1.worksheets[0].rowBreaks was empty.