appveyor.yml: finish notification test

Now it succeeds to notify. Notifying all CI success would be noisy.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62364 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

appveyor.yml

@@ -57,5 +57,6 @@ notifications:
   - provider: Slack
     incoming_webhook:
       secure: iMINHMS0nZabaDsxN9omRDsekxzVvAAzEq5ev7lN6vZ6r9zNhl3/F/7POIVyahAwVFpRDeQT/iUugpAGWmOt3eGL/lZIdqiJFZ9DjPSkP68= # #alerts
-    on_build_success: true # to test notification
+    on_build_success: false
     on_build_failure: true
+    on_build_status_changed: true