pinning `dill<0.3.9` without pinning `multiprocess` 
### Describe the bug

The [latest `multiprocess` release](https://github.com/uqfoundation/multiprocess/releases/tag/0.70.17) requires `dill>=0.3.9` which causes issues when installing `datasets` without backtracking during package version resolution. Is it possible to add a pin for multiprocess so something like `multiprocess<=0.70.16` so that the `dill` version is compatible?

### Steps to reproduce the bug

NA

### Expected behavior

NA

### Environment info

NA