Update time zone data files to tzdata release 2026b.

Update time zone data files to tzdata release 2026b.

British Columbia (America/Vancouver) moved to permanent UTC-07 on
2026-03-09, which will affect their clocks beginning on 2026-11-01.
For lack of any clarity on the point, assume their TZ abbreviation
will be MST from that time forward.

Moldova (Europe/Chisinau) has followed EU DST transition times since
2022.

Backpatch-through: 14