LLM Course chapter 3 mistakes in content

I found some content issues in chapter 3. Fine-Tuning a Pretrained Model.

1. Like issue #926 mentions, this "--upgrade" line needs to be added to all of the notebooks: %pip install --upgrade datasets

2. Three or four subsections have AdamW incorrectly imported from transformers in their notebooks, which doesn't work:

from transformers import AdamW, AutoModelForSequenceClassification, get_scheduler

AdamW should be imported from torch.optim like this:

from torch.optim import AdamW
from transformers import AutoModelForSequenceClassification, get_scheduler

3. In subsection 5, Understanding Learning Curves, the graph under "Accuracy Curves" is incorrect. It's another graph of a loss curve.

4. In subsection 5, Understanding Learning Curves, under "Solutions for erratic curves:" after "In the sample below, we lower the learning rate and increase the batch size." it has:

-learning_rate=1e-5,
+learning_rate=1e-4,

That is incorrectly showing an increase in the learning rate--the minus sign indicating replacing 0.00001 with plus sign 0.0001. 1e-4 is higher (greater) than 1e-5 so it is not "lowering" the learning rate. For example, increasing the learning rate from 1e-5 to 1e-4 means the model will take larger steps during training.