fix:distinct relations in load_graph (#9)

Author: Howe829

servers/mcp-neo4j-memory/src/mcp_neo4j_memory/server.py

@@ -68,7 +68,7 @@ async def load_graph(self, filter_query="*"):
                 type: entity.type, 
                 observations: entity.observations
             }) as nodes,
-            collect({
+            collect(distinct {
                 source: startNode(r).name, 
                 target: endNode(r).name, 
                 relationType: type(r)