.travis.yml in progress-3.5.0 vs .travis.yml in progress-3.5.1

@@ -1,23 +1,23 @@
 sudo: false
 language: ruby
 before_install:
-  - gem update bundler
+  - gem install bundler || gem install bundler --version '< 2'
 rvm:
   - '1.9.3-p551'
   - '2.0.0-p648'
   - '2.1.10'
   - '2.2.10'
   - '2.3.8'
-  - '2.4.5'
-  - '2.5.3'
-  - 'jruby-9.0.5.0'
+  - '2.4.6'
+  - '2.5.5'
+  - '2.6.3'
   - 'jruby-9.1.9.0'
 script: bundle exec rspec
 matrix:
   include:
     - env: RUBOCOP=✓
-      rvm: '2.4.5'
+      rvm: '2.4.6'
       script: bundle exec rubocop
     - env: CHECK_RUBIES=✓
-      rvm: '2.4.5'
+      rvm: '2.4.6'
       script: bundle exec travis_check_rubies