🐛 fix(utils.py): add import_retriever function to import retriever module

✨ feat(utils.py): add support for importing retriever module based on retriever name
The `import_retriever` function is added to the `utils.py` module to allow importing the retriever module based on the retriever name. This function uses the `import_module` function from the `importlib` module to dynamically import the retriever module from the `langchain.retrievers` package. This enhances the modularity and extensibility of the codebase by providing a convenient way to import retrievers based on their names.

src/backend/langflow/interface/importing/utils.py

@@ -44,6 +44,7 @@ def import_by_type(_type: str, name: str) -> Any:
         "documentloaders": import_documentloader,
         "textsplitters": import_textsplitter,
         "utilities": import_utility,
+        "retrievers": import_retriever,
     }
     if _type == "llms":
         key = "chat" if "chat" in name.lower() else "llm"
@@ -59,6 +60,11 @@ def import_chat_llm(llm: str) -> BaseChatModel:
     return import_class(f"langchain.chat_models.{llm}")
 
 
+def import_retriever(retriever: str) -> Any:
+    """Import retriever from retriever name"""
+    return import_module(f"from langchain.retrievers import {retriever}")
+
+
 def import_memory(memory: str) -> Any:
     """Import memory from memory name"""
     return import_module(f"from langchain.memory import {memory}")