Remove webhook notification to Travis CI [skip ci]

As travis-rubies now uses 3 Mac jobs to create archives for various OS
  releases.

  This is a bit wasteful if multiple builds pass in a short period.

  Instead, Travis CI is now running a nightly build of ruby-head
  (around 22:30 UTC). This will happen regardless of the state of the
  master branch.

  Author: Hiro Asari <asari.ruby@gmail.com>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56821 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

.travis.yml

@@ -73,13 +73,6 @@ notifications:
     template:
       - "%{message} by @%{author}: See %{build_url}"
 
-  # Update ruby-head installed on Travis CI so other projects can test against it.
-  webhooks:
-    urls:
-      - "https://rubies.travis-ci.org/rebuild/ruby-head"
-    on_success: always
-    on_failure: never
-
   email:
     - ko1c-failure@atdot.net
     - shibata.hiroshi@gmail.com