fix: dill default for version bigger 0.3.8
`datasets` doesn't support `dill` 0.3.9 yet afaik since `dill` made some changes related to the determinism of dumps

It would be cool to investigate (maybe run the `datasets` test) with recent `dill` to see excactly what breaks and if we can make `dill` 0.3.9 work with `datasets`
Fixes def log for dill version >= 0.3.9 
https://pypi.org/project/dill/

This project uses dill with the release of version 0.3.9 the datasets lib. 