Update freenode server name [ci skip]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56351 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

.travis.yml

@@ -66,8 +66,8 @@ branches:
 notifications:
   irc:
     channels:
-      - "irc.freenode.org#ruby-core"
-      - "irc.freenode.org#ruby-ja"
+      - "chat.freenode.net#ruby-core"
+      - "chat.freenode.net#ruby-ja"
     on_success: change # [always|never|change] # default: always
     on_failure: always # [always|never|change] # default: always
     template: