Fixed typo in django/utils/datastructures.py.

django/utils/datastructures.py

@@ -193,7 +193,7 @@ class MultiValueDict(dict):
     def update(self, *args, **kwargs):
         """Extend rather than replace existing key lists."""
         if len(args) > 1:
-            raise TypeError("update expected at most 1 arguments, got %d" % len(args))
+            raise TypeError("update expected at most 1 argument, got %d" % len(args))
         if args:
             other_dict = args[0]
             if isinstance(other_dict, MultiValueDict):