duration should not contain day component, unless MultidayEvent

[nickevansuk]

Applying rules:

• duration should not contain day component, unless MultidayEvent (duration should not contain day component, unless MultidayEvent openactive-archive/developer-microsite#25)

Not like this:

{
  "@context": "https://www.openactive.io/ns/oa.jsonld",
  "type": "Event",
  "duration": "P0DT3H0M0S"
}

Like this:

{
  "@context": "https://www.openactive.io/ns/oa.jsonld",
  "type": "Event",
  "duration": "PT3H0M0S" /* duration should not contain day component */
}