fix:to compatible with chroma old collection

dbgpt/storage/vector_store/chroma_store.py

@@ -17,6 +17,7 @@
 
 logger = logging.getLogger(__name__)
 
+CHROMA_COLLECTION_NAME = "langchain"
 
 @register_resource(
     _("Chroma Vector Store"),
@@ -81,7 +82,7 @@ def __init__(self, vector_store_config: ChromaVectorConfig) -> None:
             "hnsw:space": "cosine"
         }
         self._collection = self._chroma_client.get_or_create_collection(
-            name=vector_store_config.name,
+            name=CHROMA_COLLECTION_NAME,
             embedding_function=None,
             metadata=collection_metadata,
         )
@@ -151,6 +152,7 @@ def vector_name_exists(self) -> bool:
         files = list(filter(lambda f: f != "chroma.sqlite3", files))
         return len(files) > 0
 
+
     def load_document(self, chunks: List[Chunk]) -> List[str]:
         """Load document to vector store."""
         logger.info("ChromaStore load document")