The country code listed in the table for Ukraine
was incorrectly specified as UK, resulting in
the fallback address format being used for UA
addresses.

When setting the GtkCalendar date when clicking the date
button when using "Leave By" or "Arrive By" we need to
subtact one to the month value, as the select_month()
method expects 0-based months.

When quitting through closing the window, the contact
store is disposed in the final GJS GC sweep, which
seems to cause some race condition with respect to
the main loop.
As a workaround to this, manually dispose the store
in this callback, and set it to null.
Also guard some calls involving contact store with
nullish checks to avoid possible use-after-free.

Cherry-picked from !229