Data validation not working on copy paste

## 🐛 Bug Report

I added datavalidations to cell to throw error for duplicate value like this
```
cell.dataValidation = {
type: 'custom',
formulae: [`COUNTIF($A$${2}:$A$20,A${rowNumber})<2`],
showErrorMessage: true,
errorTitle: 'Duplicate value',
error: 'Please enter a valid value',
}
```
It works fine if I type the value in cell but if I copy paste the duplicated value it didn't work fine

Lib version: "exceljs": "^4.4.0",

## Steps To Reproduce

I have attached a xlsx file User-onboarding-template (9).xlsx and video for reference

[User-onboarding-template (9).xlsx](https://github.com/exceljs/exceljs/files/14450695/User-onboarding-template.9.xlsx)

https://github.com/exceljs/exceljs/assets/84082060/48ab2098-46ba-4ec5-8429-76ac3939ef6a

## The expected behaviour:

Data validation should work on typing as well as copy paste