Depend on sassc-rails, specify required_ruby_version

Author: glebm

.travis.yml

@@ -1,7 +1,7 @@
 language: ruby
 sudo: false
 rvm:
-  - 2.3.1
+  - 2.3.8
 gemfile:
   - test/gemfiles/rails_4_2.gemfile
   - test/gemfiles/rails_5_0.gemfile

bootstrap.gemspec

@@ -11,9 +11,12 @@ Gem::Specification.new do |s|
   s.homepage = 'https://github.com/twbs/bootstrap-rubygem'
   s.license  = 'MIT'
 
+  # SassC requires Ruby 2.3.3. Also specify here to make it obvious.
+  s.required_ruby_version = '>= 2.3.3'
+
   s.add_runtime_dependency 'popper_js', '>= 1.14.3', '< 2'
 
-  s.add_runtime_dependency 'sassc', '>= 1.12.1'
+  s.add_runtime_dependency 'sassc-rails', '>= 2.0.0'
   s.add_runtime_dependency 'autoprefixer-rails', '>= 9.1.0'
 
   # Testing dependencies

lib/bootstrap/engine.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require 'autoprefixer-rails'
+require 'sassc-rails'
 
 module Bootstrap
   module Rails