.travis.yml in micropub-endpoint-1.0.3 vs .travis.yml in micropub-endpoint-1.0.4

@@ -1,13 +1,14 @@
 language: ruby
 rvm:
-  - 2.4.5
-  - 2.5.3
-  - 2.6.0
+  - 2.4.6
+  - 2.5.5
+  - 2.6.2
 cache:
   - bundler
 before_install:
-  - gem install bundler -v '~> 1.17'
+  - gem update --system
+  - gem install bundler
 before_script:
   - curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter
   - chmod +x ./cc-test-reporter
   - ./cc-test-reporter before-build
 script: