fix: Model::set() does not accept object

[kenjis]

Description
See https://forum.codeigniter.com/showthread.php?tid=90502

When you need a more flexible solution, you can leave the parameters empty and it functions like the Query Builder’s update command, with the added benefit of validation, events, etc:
https://codeigniter4.github.io/CodeIgniter4/models/model.html#update

So, Model::set() should accept object or Entity.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide