misc/zoneinfo: Update to 2026a
Changes to past and future timestamps:
- Since 2022 Moldova has observed EU transition times, that is, it has sprung forward at 03:00, not 02:00, and has fallen back at 04:00, not 03:00.
Changes to data:
- Remove Europe/Chisinau from zonenow.tab, as it now agrees with Europe/Athens for future timestamps.