gh-148726: Add gc changes to What's New (#149398)

Author: hugovk

Doc/whatsnew/3.15.rst

@@ -1005,15 +1005,6 @@ difflib
   (Contributed by Jiahao Li in :gh:`134580`.)
 
 
-faulthandler
-------------
-
-* Added the *max_threads* parameter in :func:`faulthandler.enable`,
-  :func:`faulthandler.dump_traceback`, :func:`faulthandler.dump_traceback_later`,
-  and :func:`faulthandler.register`.
-  (Contributed by Eric Froemling in :gh:`149085`.)
-
-
 email
 -----
 
@@ -1024,6 +1015,15 @@ email
   (Contributed by R David Murray and Mike Edmunds in :gh:`122540`.)
 
 
+faulthandler
+------------
+
+* Added the *max_threads* parameter in :func:`faulthandler.enable`,
+  :func:`faulthandler.dump_traceback`, :func:`faulthandler.dump_traceback_later`,
+  and :func:`faulthandler.register`.
+  (Contributed by Eric Froemling in :gh:`149085`.)
+
+
 functools
 ---------
 
@@ -1036,6 +1036,17 @@ functools
   (Contributed by Bartosz Sławecki in :gh:`143535`.)
 
 
+gc
+--
+
+* Python 3.14.0-3.14.4 shipped with a new incremental garbage collector.
+  However, due to a number of `reports
+  <https://github.com/python/cpython/issues/142516>`__
+  of significant memory pressure in production environments,
+  it has been reverted back to the generational GC from 3.13.
+  This is the GC now used in Python 3.14.5 and later and Python 3.15.
+
+
 hashlib
 -------