Support phpspreadsheet 3

Problem/Motivation

We use the Webform XLSX export module on one of our sites, only we have the problem while updating the module that the version cannot be increased because the Excel importer module expects phpspreadsheet version 1.5.

Since Webform XLSX export will almost make a switch to phpspreadsheet version 3, I wanted to ask if it would be possible to look into doing the same for this module.

PHP requirements don't seem that different from the 2.3 version, so I hope the change will be minimal for this module.

Link to the change log:

https://github.com/PHPOffice/PhpSpreadsheet/blob/master/CHANGELOG.md#202...

Link to the referenced ticket:

https://www.drupal.org/project/webform_xlsx_export/issues/3479307 ✨ Support phpspreadsheet 3 Active

I am open to testing the changes or if I am pointed in the right direction to implement this myself.

Steps to reproduce

Install the Excel Importer module and then try installing the latest version of the Webform XLSX export → module.

Composer returns the error "Your requirements could not be resolved to an installable set of packages."

Proposed resolution

Update to version 3 of the phpspreadsheet package.

Remaining tasks

1. Implement the changes
2. Make an MR
3. Test the changes
4. Merge the code

User interface changes

none

API changes

none

Data model changes

none