load_in_8bit deprecated in llama rl script

[HassanJbara]

Running the script in examples/research_projects/stack_llama/scripts/rl_training.py with the following command:

accelerate launch --multi_gpu --num_machines 1  --num_processes 4 llama_example.py --model_name meta-llama/Llama-2-7b-chat-hf 
--tokenizer_name meta-llama/Llama-2-7b-chat-hf --log_with wandb --reward_model text-classification:Hello-SimpleAI/chatgpt-detector-roberta

produces the following error messages:

The `load_in_4bit` and `load_in_8bit` arguments are deprecated and will be removed in the future versions. Please, pass a `BitsAndBytesConfig` object in `quantization_config` argument instead.
raise ImportError(
ImportError: Using `bitsandbytes` 8-bit quantization requires Accelerate: `pip install accelerate` and the latest version of bitsandbytes: `pip install -i https://pypi.org/simple/ bitsandbytes`

Latest version of all the libraries.

trl=0.7.11
accelerate=0.27.2
torch=2.0.1
transformers=4.38.1

I assume that the script needs updating.