🐛 Bug Report

When trying to use insertRow (or insertRows) method I getting error:
TypeError: worksheet.insertRow is not a function

Lib version: "4.0.1"

Steps To Reproduce

const workbook = new Excel.Workbook()
const worksheet = workbook.addWorksheet('demo')
worksheet.insertRow(1, [3, 'Sam', new Date()])

The expected behaviour:

https://github.com/exceljs/exceljs#insert-rows