title: Installed Ruby version are different in macOS and Bundle
body: <p>I'm not using RVM but brew to install and update Ruby and Gem version up-to-date. But when I was trying <code>bundle install</code>, I got an error showed that the Ruby version requirement does not conform.</p>
  
  <p>I added <code>ruby '2.1.9'</code> to the Gemfile and did some check:</p>
  
  <pre><code>(●—●) ↪ bundle platform                                                                                
  Your platform is: universal.x86_64-darwin16
  
  Your app has gems that work on these platforms:
  * ruby
  
  Your Gemfile specifies a Ruby version requirement:
  * ruby 2.1.9
  
  Your Ruby version is 2.0.0, but your Gemfile specified 2.1.9
  (●—●) ↪ ruby -v                                                                                         
  ruby 2.4.0p0 (2016-12-24 revision 57164) [x86_64-darwin16]
  (●—●) ↪ gem -v                                                                                         
  2.6.11
  </code></pre>
  
  <p>I found that there is a lower version Ruby in my project. </p>
  
  <p><code>/Users/veck/Desktop/Project/vendor/bundle/ruby/2.0.0</code></p>
  
  <p>How do I fix this problem?</p>