.travis.yml in r10k-3.3.3 vs .travis.yml in r10k-3.4.0

@@ -11,9 +11,11 @@
   - openjdk8
 before_install: gem install bundler -v '< 2' --no-document
 matrix:
   include:
     - stage: r10k tests
+      rvm: 2.6.5
+    - stage: r10k tests
       rvm: 2.5.0
     - stage: r10k tests
       rvm: 2.4.0
     - stage: r10k tests
       rvm: 2.3.0