refine prompt of graph memory extract entities for search (#2013)

mem0/memory/graph_memory.py

@@ -175,7 +175,7 @@ def _search(self, query, filters, limit=100):
             messages=[
                 {
                     "role": "system",
-                    "content": f"You are a smart assistant who understands the entities, their types, and relations in a given text. If user message contains self reference such as 'I', 'me', 'my' etc. then use {filters['user_id']} as the source node. Extract the entities.",
+                    "content": f"You are a smart assistant who understands the entities, their types, and relations in a given text. If user message contains self reference such as 'I', 'me', 'my' etc. then use {filters['user_id']} as the source node. Extract the entities. ***DO NOT*** answer the question itself if the given text is a question.",
                 },
                 {"role": "user", "content": query},
             ],