fix: Text generator function in Scipy tutorial not sampling words based on calculated probabilities

[apoorvasheera]

Notebook - SciPy2024/module1/1-introduction-to-language-models.ipynb
Function - text_generator

next word is chosen based on below code:

word = model_sorted_probabilities[
np.random.choice(np.arange(len(model_sorted_probabilities)))
][0]

Should be something like this instead:

words = [item[0] for item in model_sorted_probabilities] # Get list of words
probabilities = [item[1] for item in model_sorted_probabilities] # Get corresponding probabilities
word = np.random.choice(words, p=probabilities) # Select based on probabilities