remove mention to improvements done during alpha release

Author: picnixz

Doc/whatsnew/3.14.rst

@@ -2323,8 +2323,7 @@ uuid
   * :func:`~uuid.uuid3` and :func:`~uuid.uuid5` are both roughly 40% faster
     for 16-byte names and 20% faster for 1024-byte names. Performance for
     longer names remains unchanged.
-  * :func:`~uuid.uuid4` and :func:`~uuid.uuid8` are 30% and 40% faster
-    respectively.
+  * :func:`~uuid.uuid4` is 30% faster.
 
   (Contributed by Bénédikt Tran in :gh:`128150`.)