Replace ezyang/htmlpurifier (LGPL2.1) with tgalopin/html-sanitizer (M…

[sweoggy]

…IT) due to more permissive license

This is:

- [x] a bugfix
- [ ] a new feature

Checklist:

• Changes are covered by unit tests (they pass, so functionality is intact)
• Code style is respected
• Commit message explains why the change is made (see https://github.com/erlang/otp/wiki/Writing-good-commit-messages)
• CHANGELOG.md contains a short summary of the change
• Documentation is updated as necessary

Why this change is needed?

This library is licensed under MIT, however the direct dependency ezyang/htmlpurifier is licensed under LGPL2.1 potentially causing licensing issues for end users of PhpSpreadsheet.

[oleibman]

The suggested package is abandoned. The replacement which it suggests is usable only with Php8.1+, and we are probably 2 years away from that requirement. I am considering whether to move forward with similar change PR #3695 instead. Regardless, I am closing this ticket.