close email notification

Signed-off-by: 高汝彤 <rutong.grt@alibaba-inc.com>

.travis.yml

@@ -12,8 +12,8 @@ install:
   - glide install
 
 notifications:
-  notifications:
     webhooks: https://oapi.dingtalk.com/robot/send?access_token=096ed387df243a6d60835aadeccc47165f3813bc7cb81cdd0cfeadfd28e3acc1
+    email: false
     on_success: always
     on_failure: always