.travis.yml in twilio-ruby-3.7.0 vs .travis.yml in twilio-ruby-3.7.1

@@ -2,9 +2,7 @@
 script: "rake spec"
 rvm:
   - 1.8.7
   - 1.9.2
   - 1.9.3
-  - rbx-18mode
-  - rbx-19mode
   - ruby-head
   - ree