fix: Add mixbai models (#1540)

for #1515

mteb/models/mxbai_models.py

@@ -27,4 +27,55 @@
     similarity_fn_name="cosine",
     framework=["Sentence Transformers", "PyTorch"],
     use_instructions=True,
+    adapted_from=None,
+    supersedes=None,
+)
+
+mxbai_embed_2d_large_v1 = ModelMeta(
+    loader=partial(
+        sentence_transformers_loader,
+        model_name="mixedbread-ai/mxbai-embed-2d-large-v1",
+        revision="7e639ca8e344af398876ead3b19ec3c0b9068f49",
+    ),
+    name="mixedbread-ai/mxbai-embed-2d-large-v1",
+    languages=["eng_Latn"],
+    open_weights=True,
+    revision="7e639ca8e344af398876ead3b19ec3c0b9068f49",
+    release_date="2024-03-04",  # initial commit of hf model.
+    n_parameters=335_000_000,
+    memory_usage=None,
+    max_tokens=512,
+    embed_dim=768,
+    license="apache-2.0",
+    reference="https://huggingface.co/mixedbread-ai/mxbai-embed-2d-large-v1",
+    similarity_fn_name="cosine",
+    framework=["Sentence Transformers", "PyTorch"],
+    use_instructions=True,
+    adapted_from=None,
+    supersedes=None,
+)
+
+
+mxbai_embed_xsmall_v1 = ModelMeta(
+    loader=partial(
+        sentence_transformers_loader,
+        model_name="mixedbread-ai/mxbai-embed-xsmall-v1",
+        revision="2f741ec33328bb57e4704e1238fc59a4a5745705",
+    ),
+    name="mixedbread-ai/mxbai-embed-xsmall-v1",
+    languages=["eng_Latn"],
+    open_weights=True,
+    revision="2f741ec33328bb57e4704e1238fc59a4a5745705",
+    release_date="2024-08-13",  # initial commit of hf model.
+    n_parameters=24_100_000,
+    memory_usage=None,
+    max_tokens=512,
+    embed_dim=384,
+    license="apache-2.0",
+    reference="https://huggingface.co/mixedbread-ai/mxbai-embed-xsmall-v1",
+    similarity_fn_name="cosine",
+    framework=["Sentence Transformers", "PyTorch"],
+    use_instructions=True,
+    adapted_from="sentence-transformers/all-MiniLM-L6-v2",
+    supersedes=None,
 )