fix: update default Cohere rerank model to rerank-v4.0-fast

flowsettings.py

@@ -310,7 +310,7 @@ KH_EMBEDDINGS["mistral"] = {
 KH_RERANKINGS["cohere"] = {
     "spec": {
         "__type__": "kotaemon.rerankings.CohereReranking",
-        "model_name": "rerank-multilingual-v2.0",
+        "model_name": "rerank-v4.0-fast",
         "cohere_api_key": config("COHERE_API_KEY", default=""),
     },
     "default": True,

libs/kotaemon/kotaemon/indices/rankings/cohere.py

@@ -8,7 +8,7 @@ from .base import BaseReranking
 
 
 class CohereReranking(BaseReranking):
-    model_name: str = "rerank-multilingual-v2.0"
+    model_name: str = "rerank-v4.0-fast"
     cohere_api_key: str = config("COHERE_API_KEY", "")
     use_key_from_ktem: bool = False
 

libs/kotaemon/kotaemon/rerankings/cohere.py

@@ -13,10 +13,11 @@ class CohereReranking(BaseReranking):
     """Cohere Reranking model"""
 
     model_name: str = Param(
-        "rerank-multilingual-v2.0",
+        "rerank-v4.0-fast",
         help=(
-            "ID of the model to use. You can go to [Supported Models]"
-            "(https://docs.cohere.com/docs/rerank-2) to see the supported models"
+            "ID of the model to use. See [Cohere Rerank models]"
+            "(https://docs.cohere.com/docs/models#rerank) for supported IDs "
+            "(e.g. rerank-v4.0-fast, rerank-v4.0-pro, rerank-multilingual-v3.0)."
         ),
         required=True,
     )

libs/ktem/ktem/pages/setup.py

@@ -226,7 +226,7 @@ class SetupPage(BasePage):
                     name="cohere",
                     spec={
                         "__type__": "kotaemon.rerankings.CohereReranking",
-                        "model_name": "rerank-multilingual-v2.0",
+                        "model_name": "rerank-v4.0-fast",
                         "cohere_api_key": cohere_api_key,
                     },
                     default=True,