Exclude deprecated rubies

Author: bf4

.travis.yml

@@ -40,6 +40,8 @@ matrix:
   # - { rvm: jruby-head,     jdk: oraclejdk8, env: "RAILS_VERSION=5.1 JRUBY_OPTS='--dev -J-Xmx1024M --debug'" }
   exclude:
   - { rvm: 2.1.10,        env: RAILS_VERSION=master }
+  - { rvm: 2.2.8,        env: RAILS_VERSION=master }
+  - { rvm: 2.3.5,        env: RAILS_VERSION=master }
   - { rvm: 2.1.10,        env: RAILS_VERSION=5.0 }
   - { rvm: 2.1.10,        env: RAILS_VERSION=5.1 }
   - { rvm: 2.4.2,         env: RAILS_VERSION=4.1 }