Remove dependency on phpoffice/phpexcel

We seem to be running into the same issue in our project.

There is a migration guide to help with moving to phpoffice/phpspreadsheet:
https://phpspreadsheet.readthedocs.io/en/latest/topics/migration-from-PHPExcel/

unqunq → changed the visibility of the branch 3423921-update-dependency to hidden.

@sboden → Would you be able to test, please?

I tested the fix provided by @unqunq and exporting to xlsx is working fine.

It's ok now. This one can be closed.
Thanks.

Not merged, yet. I don't know how to grab the maintainers' attention.

I've contacted the maintainers using their contact form, let's see if it helps moving this issue forward. Thanks for the patch!

So, this should be fixed with a new release, but in the meantime, the dev version should work.

Automatically closed - issue fixed for 2 weeks with no activity.