data: Add 2024b

[github-actions]

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

Release 2024b - 2024-09-04 12:27:47 -0700

  Briefly:
    Improve historical data for Mexico, Mongolia, and Portugal.
    System V names are now obsolescent.

  Changes to past timestamps

    Asia/Choibalsan is now an alias for Asia/Ulaanbaatar rather than
    being a separate Zone with differing behavior before April 2008.
    This seems better given our wildly conflicting information about
    Mongolia's time zone history.  (Thanks to Heitor David Pinto.)

    Historical transitions for Mexico have been updated based on
    official Mexican decrees.  The affected timestamps occur during
    the years 1921-1927, 1931, 1945, 1949-1970, and 1981-1997.
    The affected zones are America/Bahia_Banderas, America/Cancun,
    America/Chihuahua, America/Ciudad_Juarez, America/Hermosillo,
    America/Mazatlan, America/Merida, America/Mexico_City,
    America/Monterrey, America/Ojinaga, and America/Tijuana.
    (Thanks to Heitor David Pinto.)

    Historical transitions for Portugal, represented by Europe/Lisbon,
    Atlantic/Azores, and Atlantic/Madeira, have been updated based on a
    close reading of old Portuguese legislation, replacing previous data
    mainly originating from Whitman and Shanks & Pottenger.  These
    changes affect a few transitions in 1917-1921, 1924, and 1940
    throughout these regions by a few hours or days, and various
    timestamps between 1977 and 1993 depending on the region.  In
    particular, the Azores and Madeira did not observe DST from 1977 to
    1981.  Additionally, the adoption of standard zonal time in former
    Portuguese colonies have been adjusted: Africa/Maputo in 1909, and
    Asia/Dili by 22 minutes at the start of 1912.
    (Thanks to Tim Parenti.)

  Changes to past tm_isdst flags

    The period from 1966-04-03 through 1966-10-02 in Portugal is now
    modeled as DST, to more closely reflect how contemporaneous changes
    in law entered into force.

  Changes to data

    Names present only for compatibility with UNIX System V
    (last released in the 1990s) have been moved to 'backward'.
    These names, which for post-1970 timestamps mostly just duplicate
    data of geographical names, were confusing downstream uses.
    Names moved to 'backward' are now links to geographical names.
    This affects behavior for TZ='EET' for some pre-1981 timestamps,
    for TZ='CET' for some pre-1947 timestamps, and for TZ='WET' for
    some pre-1996 timestamps.  Also, TZ='MET' now behaves like
    TZ='CET' and so uses the abbreviation "CET" rather than "MET".
    Those needing the previous TZDB behavior, which does not match any
    real-world clocks, can find the old entries in 'backzone'.
    (Problem reported by Justin Grant.)

[gilmoreorless]

Tests are currently failing but aren't being reported on this PR, I'll have to fix them manually.