.travis.yml in rambling-trie-0.8.0 vs .travis.yml in rambling-trie-0.8.1

@@ -2,10 +2,15 @@
 before_install:
   - gem install bundler
 install:
   - bundle install --without test
 rvm:
+  - 2.3.3
+  - 2.3.2
+  - 2.3.1
   - 2.3.0
+  - 2.2.6
+  - 2.2.5
   - 2.2.4
   - 2.2.3
   - 2.2.2
   - 2.2.1
   - 2.2.0