CI fix clean_skops.py

[adrinjalali]

Fixes #231

This fixes the broken clean_skops.py.

• We can now pass the token to the client instance
• The output of list_models is a generator now
• Most models are private, so the token was required to list them, which were previously ignored

cc @skops-dev/maintainers

The script works locally now.

[BenjaminBossan]

Thanks for fixing this.