Use transformers utilities when possible

[qgallouedec]

What does this PR do?

A lot of utilities are redefined when we can just rely on transformers. I've removed most on them.
Most of https://github.com/huggingface/trl/blob/5c195eb51347ac4df7427eff4f1d636e860d13bf/tests/testing_utils.py

• is_bitsandbytes_available
• is_liger_available
• is_peft_available
• is_pil_available
• is_wandb_available
• is_xpu_available
• require_peft
• require_bitsandbytes
• require_diffusers
• requires_pil
• require_wandb
• require_torch_multi_gpu
• require_torch_gpu
• require_torch_multi_xpu
• require_liger_kernel
• require_non_cpu
• require_multi_accelerator

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• Did you write any new necessary tests?

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[kashif]

@qgallouedec if we are using the helpers from transformers we might need to update the minimal transformer version to something newer? see here https://github.com/huggingface/trl/blob/main/setup.py#L80

[qgallouedec]

Good point. In 4.39, we miss:

• is_torch_mlu_available (added in 4.40)
• is_liger_kernel_available (added in 4.45)

[lewtun]

Thanks for the QoL improvement! I wonder if putting a lower bound on transformers leads to downstream issues in users who have a pinned, lower version of the lib? Otherwise LGTM

[qgallouedec]

Thanks for the QoL improvement! I wonder if putting a lower bound on transformers leads to downstream issues in users who have a pinned, lower version of the lib? Otherwise LGTM

pip will probably outputs something like:

trl 0.11 requires transformers>=4.40, but you have transformers 4.35 which is incompatible.