What's new in 3.10: fix link to issue (pythonGH-93968)

* What's new in 3.10: fix link to issue

* What's new in 3.10: fix link to GH issue

Co-authored-by: Ezio Melotti <[email protected]>

Co-authored-by: Ezio Melotti <[email protected]>
(cherry picked from commit 59c1b33)

Co-authored-by: Hugo van Kemenade <[email protected]>

Author: hugovk

Doc/whatsnew/3.10.rst

@@ -1742,7 +1742,7 @@ Deprecated
 
   * ``threading.Thread.setDaemon`` => :attr:`threading.Thread.daemon`
 
-  (Contributed by Jelle Zijlstra in :issue:`21574`.)
+  (Contributed by Jelle Zijlstra in :gh:`87889`.)
 
 * :meth:`pathlib.Path.link_to` is deprecated and slated for removal in
   Python 3.12. Use :meth:`pathlib.Path.hardlink_to` instead.