MAINT Fix typo in error message when attempting to cluster with more clusters than items (scikit-learn#29242)

Co-authored-by: Jérémie du Boisberranger <jeremie@probabl.ai>

Author: jcainey

sklearn/cluster/_agglomerative.py

@@ -755,8 +755,7 @@ def _hc_cut(n_clusters, children, n_leaves):
     if n_clusters > n_leaves:
         raise ValueError(
             "Cannot extract more clusters than samples: "
-            "%s clusters where given for a tree with %s leaves."
-            % (n_clusters, n_leaves)
+            f"{n_clusters} clusters were given for a tree with {n_leaves} leaves."
         )
     # In this function, we store nodes as a heap to avoid recomputing
     # the max of the nodes: the first element is always the smallest