Support for new OPUS-MT models

[iliaschalkidis]

It seems that OPUS-MT models have been updated recently, and the library can't locate them in the old HuggingFace links...

They seem to have released what they call tc-big models, e.g., https://huggingface.co/Helsinki-NLP/opus-mt-tc-big-el-en. Is it possible to do a hotfix to support loading the new models?

With the current code, I do the following call:

from easynmt import EasyNMT

model = EasyNMT('opus-mt')

translated_sentences = model.translate('Γειά σου, τι κάνεις;',
                                                   source_lang='el',
                                                   target_lang='en',
                                                   perform_sentence_splitting=True)

and I get the following error:

Repository Not Found for url: https://huggingface.co/Helsinki-NLP/opus-mt-el-en/resolve/main/source.spm
....