What's new in 3.10: fix link to issue (GH-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 <ezio.melotti@gmail.com>

Co-authored-by: Ezio Melotti <ezio.melotti@gmail.com>
(cherry picked from commit 59c1b33)

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>

Author: miss-islington

Doc/whatsnew/3.10.rst

@@ -1746,7 +1746,7 @@ 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.