Update app.py

app.py

@@ -8,7 +8,6 @@ from haystack import Pipeline, Document
 from haystack.components.generators import OpenAIGenerator
 from haystack.components.builders.prompt_builder import PromptBuilder
 from haystack.components.embedders import SentenceTransformersDocumentEmbedder, SentenceTransformersTextEmbedder
-from haystack_integrations.document_stores.mongodb_atlas import MongoDBAtlasDocumentStore
 from haystack_integrations.components.retrievers.mongodb_atlas import MongoDBAtlasEmbeddingRetriever
 from haystack.components.embedders import OpenAITextEmbedder, OpenAIDocumentEmbedder
 from haystack.document_stores.types import DuplicatePolicy