fix blacklist addition

Author: AlejandroAvilesSerrano

nebula/core/network/communications.py

@@ -736,7 +736,7 @@ async def disconnect(self, dest_addr, mutual_disconnection=True, forced=False):
         is_neighbor = dest_addr in await self.get_addrs_current_connections(only_direct=True, myself=True)
 
         if forced:
-            self.add_to_blacklist(dest_addr)
+            await self.add_to_blacklist(dest_addr)
 
         logging.info(f"Trying to disconnect {dest_addr}")
         if dest_addr not in self.connections: