Support wkhtmltoimage

[sbidoul]

Odoo 18 uses wkhtmltoimage. We may therefore need to support that.

[dannyadair]

Thank you! Just found this issue after seeing

2025-03-06 03:01:31,538 1 INFO ? odoo.addons.base.models.ir_actions_report: Will use the Wkhtmltopdf binary at /usr/bin/wkhtmltopdf
2025-03-06 03:01:31,554 1 INFO ? odoo.addons.base.models.ir_actions_report: Wkhtmltopdf seems to be broken.
2025-03-06 03:01:31,554 1 INFO ? odoo.addons.base.models.ir_actions_report: You need Wkhtmltoimage to generate images from html.

Creating another dependency on a dead project is a little weird but at least it's only 6 out of 33 options used
https://github.com/odoo/odoo/blob/18.0/odoo/addons/base/models/ir_actions_report.py#L456C1-L498C29

Looks like only the new marketing_card addon in v18 is using it at the moment
https://github.com/odoo/odoo/blob/18.0/addons/marketing_card/models/card_campaign.py#L309

so if you don't use it it's just a warning I guess.