Fix peewee issues with pyright when updating a CharField and then saving it

[benoit74]

When updating an ORM object (e.g. book.html_etag = etag), #191 had to add # type: ignore hint because pyright was complaining that a str cannot be used to set a CharField

This is clearly a peewee issue, maybe linked to the fact that we are using an old version.

To be fixed / reported upstream if not already fixed.