.travis.yml in slack-ruby-client-0.15.1 vs .travis.yml in slack-ruby-client-0.16.0

@@ -3,21 +3,18 @@
 cache: bundler
 
 rvm:
   - 2.5.3
   - 2.6.0
+  - 2.7.1
   - ruby-head
   - jruby-head
 
 matrix:
   include:
     - rvm: 2.4.1
       script:
         - bundle exec danger
-    - rvm: 2.4.1
-      env: CONCURRENCY=celluloid-io
-    - rvm: 2.4.1
-      env: CONCURRENCY=faye-websocket
     - rvm: 2.5.3
       env: CONCURRENCY=async-websocket
   allow_failures:
     - rvm: ruby-head
     - rvm: jruby-head