gh-90153: whatsnew: "z" option in format spec (GH-93624)

Add what's new entry for PEP 682 in Python 3.11.
(cherry picked from commit 010284b)

Co-authored-by: John Belmonte <[email protected]>

Author: miss-islington

Doc/whatsnew/3.11.rst

@@ -373,6 +373,9 @@ Other Language Changes
   the current directory, the script's directory or an empty string.
   (Contributed by Victor Stinner in :gh:`57684`.)
 
+* A ``"z"`` option was added to the format specification mini-language that
+  coerces negative zero to zero after rounding to the format precision.  See
+  :pep:`682` for more details.  (Contributed by John Belmonte in :gh:`90153`.)
 
 Other CPython Implementation Changes
 ====================================