Update used bundler version

.travis.yml

@@ -6,6 +6,10 @@ rvm:
   - 2.5
   - 2.4
   - 2.3
+bundler_args: --without production
+before_install:
+  - gem update --system
+  - gem install bundler
 script:
   - export RAILS_ENV=test
   - bundle exec rake db:schema:load

Gemfile.lock

@@ -271,4 +271,4 @@ DEPENDENCIES
   will_paginate-bootstrap (~> 1.0.1)
 
 BUNDLED WITH
-   1.17.2
+   2.0.1