Add Transformer-based NER classifier using Hugging Face models

[lfcc1]

What's in the PR

• Added a TransformerNerClassifier class that allows to perform Named Entity Recognition using pre-trained models from Hugging Face's transformers.

How to test

• Run test file: pytest tests/test_transformer_recommender.py

[reckart]

@lfcc1 build fails

[lfcc1]

My bad. I commented some dependencies in the setup.py file for my specific use case. I have corrected it.

[reckart]

@lfcc1 Looks like there is still some problem with the requirements.

[lfcc1]

@reckart Missed a comma, could you try again?

[reckart]

Thanks again :)