Fix peft constructors

[Cyrilvallez]

What does this PR do?

As per the title. Fixes #45448 (comment)
cc @BenjaminBossan

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[BenjaminBossan]

Thanks for working on a fix, this resolves the failing transformers test. In PEFT, the corresponding tests are still failing, but I will port the changes from here over to PEFT and that should do the trick.

Is there any way we can make all of this more robust? It's not the first time things break. I assume this is because we rely on Transformers-internal implementation details. Is there a public, more stable API that we can use instead?

[Cyrilvallez]

Those are indeed relying on internals, which is why it wasn't detected! If you can add a simple fast test performing one of those conversions, it would catch any regresions though!

[BenjaminBossan]

@Cyrilvallez I could convert test_mixtral_lora_conversion to a normal test instead of a slow test. It uses a tiny model (7.6 MB). Locally, with the model cached, it finishes in 1.5 sec. Would that be all right?

[Cyrilvallez]

Yes 100%