fix gridfs import

Author: blink1073

gridfs/asynchronous/grid_file.py

@@ -46,7 +46,6 @@
 from pymongo.asynchronous.collection import AsyncCollection
 from pymongo.asynchronous.cursor import AsyncCursor
 from pymongo.asynchronous.database import AsyncDatabase
-from pymongo.asynchronous.helpers import anext
 from pymongo.common import validate_string
 from pymongo.errors import (
     BulkWriteError,

gridfs/synchronous/grid_file.py

@@ -57,7 +57,6 @@
 from pymongo.synchronous.collection import Collection
 from pymongo.synchronous.cursor import Cursor
 from pymongo.synchronous.database import Database
-from pymongo.synchronous.helpers import next
 
 _IS_SYNC = True