[tz] [PROPOSED 7/9] Sync Casey data from timeanddate.com

[Paul Eggert]

* NEWS: Mention this.
* antarctica (Antarctica/Casey): Add five zone changes since 2020.
---
 NEWS       |  5 +++++
 antarctica | 12 +++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index 5f8df64e..9d0341d0 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,7 @@ Unreleased, experimental changes
   Briefly:
     Ittoqqortoormiit, Greenland changes time zones on 2024-03-31.
     Vostok, Antarctica changed time zones on 2023-12-18.
+    Casey, Antarctica changed time zones five times since 2020.
     Code and data fixes for Palestine timestamps starting in 2072.
     A new data file zonenow.tab for timestamps starting now.
 
@@ -25,6 +26,10 @@ Unreleased, experimental changes
     Vostok, Antarctica changed to +05 on 2023-12-18.  It had been at
     +07 (not +06) for years.  (Thanks to Zakhary V. Akulov.)
 
+    Change data for Casey, Antarctica to agree with timeanddate.com,
+    by adding five time zone changes since 2020.  Casey is now at +08
+    instead of +11.
+
   Changes to past tm_isdst flags
 
     Much of Greenland, represented by America/Nuuk, changed its
diff --git a/antarctica b/antarctica
index 9931378b..763c2725 100644
--- a/antarctica
+++ b/antarctica
@@ -80,6 +80,11 @@
 # - 2018 Oct  7 4:00 - 2019 Mar 17 3:00 - 2019 Oct  4 3:00 - 2020 Mar  8 3:00
 # and now - 2020 Oct  4 0:01
 
+# From Paul Eggert (2023-12-20):
+# Transitions from 2021 on are taken from:
+# https://www.timeanddate.com/time/zone/antarctica/casey
+# retrieved at various dates.
+
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone Antarctica/Casey	 0	-	-00	1969
 			 8:00	-	+08	2009 Oct 18  2:00
@@ -93,7 +98,12 @@ Zone Antarctica/Casey	 0	-	-00	1969
 			 8:00	-	+08	2019 Oct  4  3:00
 			11:00	-	+11	2020 Mar  8  3:00
 			 8:00	-	+08	2020 Oct  4  0:01
-			11:00	-	+11
+			11:00	-	+11	2021 Mar 14  0:00
+			 8:00	-	+08	2021 Oct  3  0:01
+			11:00	-	+11	2022 Mar 13  0:00
+			 8:00	-	+08	2022 Oct  2  0:01
+			11:00	-	+11	2023 Mar  9  3:00
+			 8:00	-	+08
 Zone Antarctica/Davis	0	-	-00	1957 Jan 13
 			7:00	-	+07	1964 Nov
 			0	-	-00	1969 Feb
-- 
2.43.0