Prompt Learning Notebook Bug Fix
Prompt Learning Notebook Bug Fix

Signed-off-by: Virginia Adams <vadams@nvidia.com>

Adds back ability to handle dataset example dicts directly passed into the .generate method for prompt learning

**Collection**: NLP

# Changelog 
- Updated GPTPromptLearningDataset class
- Updated GPTPromptLearningModel class's generate function
- Updated prompt learning unit test

# Usage

```python
test_examples = [
    {"taskname": "intent_and_slot", "utterance": "tell me who will win the next presidential election"},
    {"taskname": "intent_and_slot", "utterance": "i would like to pickup a veggie sub with a cookie from subway"},
    {"taskname": "intent_and_slot", "utterance": "email happy new year to john"},
    {"taskname": "intent_and_slot", "utterance": "set the alarm to seven am for work"},
    {"taskname": "sentiment", "sentence": "The products have a low salt and fat content ."},
    {"taskname": "sentiment", "sentence": "The agreement is valid for four years ."},
    {"taskname": "sentiment", "sentence": "Diluted EPS rose to EUR3 .68 from EUR0 .50 ."},
    {"taskname": "sentiment", "sentence": "The company is well positioned in Brazil and Uruguay ."},
    {"taskname": "sentiment", "sentence": "Profit before taxes decreased by 9 % to EUR 187.8 mn in the first nine months of 2008 , compared to EUR 207.1 mn a year earlier ."},
]

response = model.generate(inputs=test_examples, length_params=None)
```

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**PR Type**:
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- [x] Bugfix
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# Additional Information
* Related to # (issue)
