compatibility in revised version release

[calmzhu]

In function ListBucketsHeaders's param header
it's type changed from dict( in alibabacloud-oss20190517==1.0.5) to object oss_20190517_models.ListBucketsHeader(in alibabacloud-oss20190517==1.0.5)
This is an broken change,it should NEVER be in revisied versions.

[TsinghuaDream]

Try this SDK. https://www.alibabacloud.com/help/en/oss/developer-reference/python
alibabacloud-oss20190517 is still optimized internally.