Ioki::Model::Driver::DriverRequestToken does not work because product_login_slug is missing

[eis-ioki]

On June 9th 2022 the API got an additional required parameter: product_login_slug (driver_login_slug)

This is the slug of the product, which is used by the driver.

We need to add this to make the driver API client work again. Apparently no one uses this client though, or it would have been raised by someone else by now.