contrib/tzdata: import tzdata 2024a
Changes: https://github.com/eggert/tz/blob/2024a/NEWS
(cherry picked from commit 2723c7ffb7f729a1d3f7c59e7db48b0edf3d30a6)
(cherry picked from commit f4256acec1c980b7d08e9e526be6d2a7c4751f0b)
Approved by: re (karels)