data: Add 2023b

[gilmoreorless]

This contains the following changes from tzdb (edited to remove details irrelevant to this project):

Release 2023a - 2023-03-22 12:39:33 -0700

  Changes to future timestamps

    Starting in 2023, Egypt will observe DST from April's last Friday
    through October's last Thursday.  (Thanks to Ahmad ElDardiry.)
    Assume the transition times are 00:00 and 24:00, respectively.

    In 2023 Morocco's spring-forward transition after Ramadan
    will occur April 23, not April 30.  (Thanks to Milamber.)
    Adjust predictions for future years accordingly.  This affects
    predictions for 2023, 2031, 2038, and later years.

    This year Palestine will delay its spring forward from
    March 25 to April 29 due to Ramadan.  (Thanks to Heba Hamad.)
    Make guesses for future Ramadans too.

    Much of Greenland, represented by America/Nuuk, will continue to
    observe DST using European Union rules.  When combined with
    Greenland's decision not to change the clocks in fall 2023,
    America/Nuuk therefore changes from -03/-02 to -02/-01 effective
    2023-10-29 at 01:00 UTC.  (Thanks to Thomas M. Steenholdt.)
    This change from 2022g doesn't affect timestamps until 2024-03-30,
    and doesn't affect tm_isdst until 2023-03-25.

  Changes to past timestamps

    America/Yellowknife has changed from a Zone to a backward
    compatibility Link, as it no longer differs from America/Edmonton
    since 1970.  (Thanks to Almaz Mingaleev.)  This affects some
    pre-1948 timestamps.  The old data are now in 'backzone'.

  Changes to past time zone abbreviations

    When observing Moscow time, Europe/Kirov and Europe/Volgograd now
    use the abbreviations MSK/MSD instead of numeric abbreviations,
    for consistency with other timezones observing Moscow time.

  Changes to commentary

    To improve tzselect diagnostics, zone1970.tab's comments column is
    now limited to countries that have multiple timezones.

Release 2023b - 2023-03-23 19:50:38 -0700

  Changes to future timestamps

    This year Lebanon springs forward April 20/21 not March 25/26.
    (Thanks to Saadallah Itani.)

Other changes not specifically mentioned in tzdb's NEWS file:

• America/Honolulu was removed from the UM country code (but it still included in US).
• Various region descriptions were reworded and simplified in iso3166.tab, zone.tab and zone1970.tab.