Update to ruby/spec@35a9fba

Author: eregon

spec/ruby/.travis.yml

@@ -15,14 +15,11 @@ matrix:
       env: CHECK_LEAKS=true
     - rvm: 2.6.0
       env: CHECK_LEAKS=true
-    - rvm: ruby-head
     - env: RUBOCOP=true
       rvm: 2.4.5
       script:
         - gem install rubocop:0.61.0
         - rubocop
-  allow_failures:
-    - rvm: ruby-head
 branches:
   only:
     - master