Modeling: Merge Vertices, correct spelling of report

Fix the "Merge Vertices" report, replacing "vertice(s)" with either
"vertex" or "vertices". The singular "vertice" is not a word in English,
and thus the regular "append (s)" approach is incorrect.

Pull Request: https://projects.blender.org/blender/blender/pulls/119863

source/blender/editors/mesh/editmesh_tools.cc

@@ -3584,7 +3584,10 @@ static int edbm_remove_doubles_exec(bContext *C, wmOperator *op)
     }
   }
 
-  BKE_reportf(op->reports, RPT_INFO, "Removed %d vertice(s)", count_multi);
+  BKE_reportf(op->reports,
+              RPT_INFO,
+              count_multi == 1 ? "Removed %d vertex" : "Removed %d vertices",
+              count_multi);
 
   return OPERATOR_FINISHED;
 }