Fix _Extra.split() in zipfile

Author: danny0838

Lib/zipfile/__init__.py

@@ -218,7 +218,7 @@ def split(cls, data):
         # use memoryview for zero-copy slices
         rest = memoryview(data)
         while rest:
-            extra, rest = _Extra.read_one(rest)
+            extra, rest = cls.read_one(rest)
             yield extra
 
     @classmethod