[FIX] website_event: copy website_menu when copying an event

Currently website_menu boolean field is not copied when copying an event. It
comes from an issue related to duplicating website menus. It seems real issue
has been fixed at 1a8993e0cb . Current copy=False on website_menu is a wrong fix
due to some mismatch in forward-port. We can therefore copy website_menu
again.

LINKS

Task ID 2089156
Community PR odoo/odoo#42911

addons/website_event/models/event_event.py

@@ -33,7 +33,7 @@ class Event(models.Model):
     # website
     website_published = fields.Boolean(tracking=True)
     website_menu = fields.Boolean(
-        string='Dedicated Menu', copy=False,
+        string='Dedicated Menu',
         compute='_compute_from_event_type', readonly=False, store=True,
         help="Creates menus Introduction, Location and Register on the page "
              "of the event on the website.")