Fixes issue #152 - error with creating wandb artifact

[AshisGhosh]

What this does

Quick fix for #152.

Unnecessary if the string name for the datasets change. More discussion here: f80902b

How it was tested

Ran training with a dataset with / in the string. Confirmed not to error.

Run all tests except test_examples_3_and_2. Passed.

How to checkout & try?

Run training with a dataset with / in the string. E.g.:

python lerobot/scripts/train.py     policy=act     env=aloha     env.task=AlohaInsertion-v0     dataset_repo_id=lerobot/aloha_sim_insertion_human