.travis.yml in doomfire-0.1.0 vs .travis.yml in doomfire-0.2

@@ -1,7 +1,10 @@
 ---
 sudo: false
 language: ruby
 cache: bundler
 rvm:
+  - 2.3.8
+  - 2.4.5
+  - 2.5.5
   - 2.6.2
 before_install: gem install bundler -v 2.0.1