With only the module appointment installed, go to Calendar App,
Online Appointments and click on "Create". In the form view displayed a
stat button "Customer Preview" is visible but is badly styled. This is
due to the fact that "Customer Preview" is no longer wrap by a span since
the rewriting of the form view (see odoo/odoo@48ef812a63).
We fix the problem by making the default slot content of ViewButton be a
span wrapping the prop string (if any).
Part-of: odoo/odoo#98072
Mathieu Duckerts-Antoine
64aa8dd3b0