fix: OgmaWrapper inherit from AbsEncoder (#4670)

OgmaWrapper was declared as a bare class, so isinstance(model, EncoderProtocol)
returns False and RetrievalEvaluator rejects it with TypeError. Inheriting from
AbsEncoder picks up the default similarity / similarity_pairwise implementations
driven by ModelMeta.similarity_fn_name (already set to COSINE for all Ogma
models). No change to encoding behaviour.

Reported by @Samoed on embeddings-benchmark/results#525.

Author: sam-at-axiotic

mteb/models/model_implementations/axiotic_models.py

@@ -5,6 +5,7 @@
 import numpy as np
 import torch
 
+from mteb.models.abs_encoder import AbsEncoder
 from mteb.models.model_meta import ModelMeta, ScoringFunction
 
 if TYPE_CHECKING:
@@ -23,7 +24,7 @@
 )
 
 
-class OgmaWrapper:
+class OgmaWrapper(AbsEncoder):
     """MTEB wrapper for Axiotic Ogma embedding models."""
 
     def __init__(