.travis.yml in purgatory-3.1.2 vs .travis.yml in purgatory-4.0.0

@@ -1,7 +1,10 @@
 language: ruby
 rvm:
-  - 1.9.3
-  - 2.0.0
+  - 2.2.10
+  - 2.3.8
+  - 2.4.9
+  - 2.5.7
+  - 2.6.5
 cache:
   bundler: true
 script: bundle exec rspec