Espaloma tests failing with missing DILL_AVAILABLE import

Error message:

```
E   ImportError: cannot import name 'DILL_AVAILABLE' from 'torch.utils.data.datapipes.utils.common' (/root/micromamba/envs/openfe_env/lib/python3.12/site-packages/torch/utils/data/datapipes/utils/common.py)
```

For now we can xfail the relevant test, but it likely needs an upstream fix.