Don't provide a VAC Application Deadline for elections that don't require Voter ID

[chris48s]

Currently it is possible to do something like this:

>>> from uk_election_timetables.election_ids import from_election_id
>>> timetable = from_election_id('senedd.2026-05-07')
>>> timetable.vac_application_deadline
datetime.date(2026, 4, 28)

This makes no sense because Senedd elections do not require ID to vote. This applies to:

• Senedd
• Scottish Parliament
• Local Council elections in
  • Wales
  • Scotland
  • City of London

For these cases, calling .vac_application_deadline should either:

• return None or
• throw an exception

Also, the election.timetable property should not include the VAC Application Deadline here

uk-election-timetables/uk_election_timetables/election.py

Lines 96 to 100 in 753a0d7

	{
	"label": TimetableEvent.VAC_APPLICATION_DEADLINE.value,
	"date": self.vac_application_deadline,
	"event": TimetableEvent.VAC_APPLICATION_DEADLINE.name,
	},

I think before embarking on this one I would like to have a look over the code for client applications consuming this library and work out the least disruptive way to implement this, or the likely changes needed in client apps to account for this.