.travis.yml in slack-ruby-bot-0.12.0 vs .travis.yml in slack-ruby-bot-0.13.0

@@ -2,25 +2,27 @@
 
 cache: bundler
 
 matrix:
   include:
-    - rvm: 2.3.0
+    - rvm: 2.6.5
       script:
         - bundle exec danger
     - rvm: 2.3.0
       env: CONCURRENCY=celluloid-io
     - rvm: 2.3.0
       env: CONCURRENCY=faye-websocket
     - rvm: 2.3.0
+      env: CONCURRENCY=async-websocket
+    - rvm: 2.6.5
       env: CONCURRENCY=celluloid-io WITH_GIPHY=true
-    - rvm: 2.3.0
+    - rvm: 2.6.5
       env: CONCURRENCY=faye-websocket WITH_GIPHY=true
-    - rvm: 2.3.0
+    - rvm: 2.6.5
       env: CONCURRENCY=celluloid-io WITH_GIPHY_CLIENT=true
-    - rvm: 2.3.0
+    - rvm: 2.6.5
       env: CONCURRENCY=faye-websocket WITH_GIPHY_CLIENT=true
-    - rvm: 2.5
+    - rvm: 2.6.5
       env: CONCURRENCY=async-websocket WITH_GIPHY_CLIENT=true
     - rvm: ruby-head
     - rvm: jruby-head
   allow_failures:
     - rvm: ruby-head