.travis.yml in attributor-7.1 vs .travis.yml in attributor-8.0

@@ -1,11 +1,9 @@
 sudo: false
 language: ruby
 rvm:
-  - 2.4
-  - 2.5
-  - 2.6
   - 2.7
+  - 3.2
 script:
   - bundle exec rspec spec
 branches:
   only:
     - master