fix: add gte-modernbert-base

[afalf]

Checklist

• Run tests locally to make sure nothing is broken using make test.
• Run the formatter to format the code using make lint.

Adding datasets checklist

Reason for dataset addition: ...

• [x ] I have run the following models on the task (adding the results to the pr). These can be run using the mteb -m {model_name} -t {task_name} command.
  • [x ] sentence-transformers/paraphrase-multilingual-MiniLM-L12-v2
  • [ x] intfloat/multilingual-e5-small
• [ x] I have checked that the performance is neither trivial (both models gain close to perfect scores) nor random (both models gain close to random scores).
• [ x] If the dataset is too big (e.g. >2048 examples), considering using self.stratified_subsampling() under dataset_transform()
• [x ] I have filled out the metadata object in the dataset file (find documentation on it here).
• [x ] Run tests locally to make sure nothing is broken using make test.
• [ x] Run the formatter to format the code using make lint.

Adding a model checklist

• [x ] I have filled out the ModelMeta object to the extent possible
• [ x] I have ensured that my model can be loaded using
  • [x ] mteb.get_model(model_name, revision) and
  • [x ] mteb.get_model_meta(model_name, revision)
• [ x] I have tested the implementation works on a representative set of tasks.

[Samoed]

@afalf Can you share your datasets and fill for the rest of gte models too?