The library does not support python 2

[smartlixx]

From readme, I thought the library supports python 2 and 3. But after I installed the library under python 2.7, I found 'from cdo_api_py import Client' produced a lot of errors related to python 2, e.g., 'yield from' and 'join([..., *args]).

It would be great if you can kindly modify the code to support python 2. Otherwise, change readme to inform potential users of this characteristic. it would save people a lot of time, in my opinion.