fix: update deprecated date time formats

Signed-off-by: András Felleg <73272730+Andris28@users.noreply.github.com>

Author: Andris28

src/test/java/com/ibm/cloud/sdk/core/util/DateUtilsTest.java

@@ -116,13 +116,13 @@ public void testDateTime() {
 
     // RFC 2616 HTTP Date.
     _testDateTime("Fri, 27 Aug 2021 13:15:55 GMT", "2021-08-27T13:15:55.000Z");
-    _testDateTime("Fri, 27 Aug 2021 13:15:55 CXT", "2021-08-27T06:15:55.000Z");
-    _testDateTime("Fri, 27 Aug 2021 13:15:55 VLAT", "2021-08-27T03:15:55.000Z");
+    _testDateTime("Fri, 27 Aug 2021 13:15:55 PDT", "2021-08-27T20:15:55.000Z");
+    _testDateTime("Fri, 27 Aug 2021 13:15:55 EDT", "2021-08-27T17:15:55.000Z");
 
     // RFC 850 HTTP Date.
     _testDateTime("Friday, 27-Aug-2021 13:15:55 GMT", "2021-08-27T13:15:55.000Z");
-    _testDateTime("Friday, 27-Aug-2021 13:15:55 CXT", "2021-08-27T06:15:55.000Z");
-    _testDateTime("Friday, 27-Aug-2021 13:15:55 VLAT", "2021-08-27T03:15:55.000Z");
+    _testDateTime("Friday, 27-Aug-2021 13:15:55 PDT", "2021-08-27T20:15:55.000Z");
+    _testDateTime("Friday, 27-Aug-2021 13:15:55 EDT", "2021-08-27T17:15:55.000Z");
 
     // ANSIC HTTP Date.
     _testDateTime("Fri Aug 27 13:15:55 2021", "2021-08-27T13:15:55.000Z");