Gather HF_TOKEN internally when calling Distiset.push_to_hub if token is None.

[plaguss]

Description

We will try to load the HF_TOKEN internally if possible, or raise a ValueError if not possible, to avoid propagating the error.

Closes #693

[codspeed-hq]

CodSpeed Performance Report

Merging #707 will not alter performance

_{Comparing distiset-hf-token (2b552bc) with develop (1d53ee8)}

Summary

✅ 1 untouched benchmarks