Log Message:
kcalendarcore: update to 5.108.0

5.99
  Use dtStart as the default for dtRecurrence
5.103
  Add Q_PROPERTY for IncidenceBase::url as well
  Avoid calling twice update() in setAttendees()
  Unbreak static build consumers
5.106
  Deprecate Calendar relations API
  Deprecate the notebook support
  Deprecated the non-functional and unused save/reload API