Callable context_getter prevents serialization of nlp pipeline

[theoimbert-aphp]

When using a function as a context getter in TrainableSpanClassifier and TrainableNerCrf at least, nlp.to_disk(save_path) returns an error of the type :

PydanticSerializationError: Unable to serialize unknown type: <function context_getter_function at 0x7f26ec697560>

How to reproduce the bug

import edsnlp, edsnlp.pipes as eds

# context_getter function
def context_getter_function(span):
    doc = span.doc
    return doc[max(0, span.start-15) : min(len(doc), span.end+15)]

# pipeline definition
nlp = edsnlp.blank("eds")
nlp.add_pipe(eds.sentences())
nlp.add_pipe(
    eds.span_classifier(
        embedding=eds.span_pooler(
            pooling_mode="mean",
            embedding=eds.transformer(
                model="prajjwal1/bert-tiny",
            ),
        ),
        span_getter=[
            "mobility", 
        ],
        attributes=[
            "_.negation",
        ],
        context_getter=context_getter_function
    ),
    name="span_classifier",
)

# trying to save the model
nlp.to_disk("path/to/model")

Note that using the model defined in this example for inference or training does work, it is specifically the saving part that does not.

Your Environment

• Python Version Used: 3.7.16
• EDS-NLP Version Used: 0.17.2
• spaCy: 3.7.5