[OU-FIX] calendar: Avoid fake recurrent events

If no day is selected, there's not really recurrency, and Odoo will
complain when applying it, so we prevent to insert such events in the
recurrence table.

openupgrade_scripts/scripts/calendar/14.0.1.0/post-migration.py

@@ -40,6 +40,7 @@ def fill_calendar_recurrence_table(env):
             FROM calendar_event
             WHERE recurrency AND recurrence_id IS NULL
                 AND (recurrent_id IS NULL OR recurrent_id = 0)
+                AND (mo OR tu OR we OR th OR fr OR sa OR su)
             RETURNING id,base_event_id
         )
         UPDATE calendar_event ce