Update doc/whats_new/v0.21.rst

Co-Authored-By: jeremiedbb <34657725+jeremiedbb@users.noreply.github.com>

doc/whats_new/v0.21.rst

@@ -353,7 +353,7 @@ Support for Python 3.4 and below has been officially dropped.
 - |Fix| The function :func:`euclidean_distances`, and therefore and therefore
   several estimators with ``metric=euclidean``, suffered from numerical
   precision issues with float32 features. Precision has been increased at the
-  cost of a small drop of performance. :issue:`13554` by :user:`Celelibi` and
+  cost of a small drop in performance. :issue:`13554` by :user:`Celelibi` and
   :user:`Jérémie du Boisberranger <jeremiedbb>`.
 
 - |API| :func:`metrics.jaccard_similarity_score` is deprecated in favour of