.travis.yml in fluent-plugin-webhdfs-1.3.1 vs .travis.yml in fluent-plugin-webhdfs-1.3.2

@@ -1,13 +1,14 @@
 sudo: false
 language: ruby
 
 rvm:
-  - 2.1
-  - 2.2
-  - 2.3.3
-  - 2.4.0
+  - 2.4
+  - 2.5
+  - 2.6
+  - 2.7
+  - ruby-head
 
 branches:
   only:
     - master
 
@@ -21,5 +22,9 @@
 
 script: bundle exec rake test
 
 gemfile:
   - Gemfile
+
+matrix:
+  allow_failures:
+    - rvm: ruby-head