We should await ws.send_str()

Change-Id: I263a5170c27147c8e6a77457fed3df24df65ac04
diff --git a/zuul/web/__init__.py b/zuul/web/__init__.py
index 00ac9c6..89f5efe 100755
--- a/zuul/web/__init__.py
+++ b/zuul/web/__init__.py
@@ -108,7 +108,7 @@
         except Exception as e:
             self.log.exception("Finger client exception:")
             msg = "Failure from finger client: %s" % e
-            ws.send_str(msg.decode('utf8'))
+            await ws.send_str(msg.decode('utf8'))
 
         return (1000, "No more data")