Bump version to 2020d

[pganssle]

Release 2020d - 2020-10-21 11:24:13 -0700

Briefly:

Palestine ends DST earlier than predicted, on 2020-10-24.

Changes to past and future timestamps

Palestine ends DST on 2020-10-24 at 01:00, instead of 2020-10-31
as previously predicted (thanks to Sharef Mustafa.) Its
2019-10-26 fall-back was at 00:00, not 01:00 (thanks to Steffen
Thorsen.) Its 2015-10-23 transition was at 01:00 not 00:00, and
its spring 2020 transition was on March 28 at 00:00, not March 27
(thanks to Pierre Cashon.) This affects Asia/Gaza and
Asia/Hebron. Assume future spring and fall transitions will be on
the Saturday preceding the last Sunday of March and October,
respectively.