pythongh-95913: Fix PEP number in PEP 678 What's New ref label (pythonGH-97739)

What's New: Fix PEP number in PEP 678 ref target label
(cherry picked from commit e738b51)

Co-authored-by: C.A.M. Gerlach <[email protected]>

Author: CAM-Gerlach

Doc/whatsnew/3.11.rst

@@ -191,7 +191,7 @@ See :pep:`654` for more details.
 Irit Katriel, Yury Selivanov and Guido van Rossum.)
 
 
-.. _whatsnew311-pep670:
+.. _whatsnew311-pep678:
 
 PEP 678: Exceptions can be enriched with notes
 ----------------------------------------------