fix whats-new.rst entry

Author: kmuehlbauer

doc/whats-new.rst

@@ -74,7 +74,7 @@ Internal Changes
   backend interface, so no existing code should break.
   By `Deepak Cherian <https://github.com/dcherian>`_.
 - Implement CF coding functions in ``VariableCoders``.
-  By By `Kai Mühlbauer <https://github.com/kmuehlbauer>`_
+  By `Kai Mühlbauer <https://github.com/kmuehlbauer>`_
 
 - Added a config.yml file with messages for the welcome bot when a Github user creates their first ever issue or pull request or has their first PR merged. (:issue:`7685`, :pull:`7685`)
   By `Nishtha P <https://github.com/nishthap981>`_.