drop bundler version spec; update ruby versions

Author: bolandrm

.travis.yml

@@ -13,8 +13,9 @@ gemfile:
   - gemfiles/rails_5_2.gemfile
 
 rvm:
-  - 2.4.4
-  - 2.5.1
+  - 2.4.6
+  - 2.5.5
+  - 2.6.3
   - jruby
 
 notifications:

sassc-rails.gemspec

@@ -19,7 +19,7 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.add_development_dependency 'pry'
-  spec.add_development_dependency "bundler", "~> 1.7"
+  spec.add_development_dependency "bundler"
   spec.add_development_dependency "rake", "~> 10.0"
   spec.add_development_dependency 'mocha'