Fix variable name

Author: asvetlov

aiohttp/connector.py

@@ -128,7 +128,7 @@ def close(self):
     @staticmethod
     def _do_close(conns):
         for key, data in conns.items():
-            for transport, proto, td in data:
+            for transport, proto, t0 in data:
                 transport.close()
 
         conns.clear()