Bug 9031: Unit tests for DST crossing in (days|hours)_between

Bug 9031: Unit tests for DST crossing in (days|hours)_between

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Without the patch for Calendar.pm, this crashes on:
Invalid local time for date in time zone: America/New_York

But even with the original change to Calendar.pm, I would see:
Invalid local time for date in time zone: Europe/Amsterdam
Adding a follow-up for that.

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>