.travis.yml in roxml-4.0.0 vs .travis.yml in roxml-4.1.0

@@ -1,7 +1,13 @@
 sudo: false
 language: ruby
+before_install:
+  - bundle update --bundler
 rvm:
-  - 2.2.8
-  - 2.3.5
-  - 2.4.2
+  - 2.5.3
+  - 2.6.1
+  - 2.7.1
   - ruby-head
+
+matrix:
+  allow_failures:
+    - rvm: ruby-head