.travis.yml in email_inquire-0.7.0 vs .travis.yml in email_inquire-0.8.0

@@ -1,15 +1,15 @@
 before_install:
-  - gem install bundler -v 1.15.0
+  - gem update --system
+  - gem update bundler
 before_script:
   - cp -f .rspec.travis .rspec
 bundler_args: --without local
 dist: trusty
 language: ruby
 rvm:
-  - 2.1.10
-  - 2.2.7
-  - 2.3.4
-  - 2.4.1
+  - 2.3.6
+  - 2.4.3
+  - 2.5.0
 script:
   - bundle exec rake ci
 sudo: false