title: Stale Asset - Hanami does not update the edited files
body: <p>I'm using Hanami with sass as preprocessor, but when I make changes in some .scss file and refresh the page the changes don't load, the <strong>public/assets/<em>file</em>.css</strong> is not updating. For update I have to delete the file...</p>
  
  <p>Does anyone know why this happens?</p>
  
  <p>Gemfile</p>
  
  <pre><code>source 'https://rubygems.org'
  
  gem 'bundler'
  gem 'rake'
  gem 'hanami',       '0.7.3'
  gem 'hanami-model', '~&gt; 0.5'
  
  gem "sass"
  gem 'pg'
  
  group :test do
    gem 'minitest'
    gem 'capybara'
  end
  
  group :production do
    # gem 'puma'
  end
  </code></pre>
  
  <p>application.rb</p>
  
  <pre><code>...
  
  assets do
          ...
          # Stylesheet compressor
          #
          # Supported engines:
          #
          #   * :builtin
          #   * :yui
          #   * :sass
          #
          # See: http://hanamirb.org/guides/assets/compressors
          #
          # In order to skip stylesheet compression comment the following line
          stylesheet_compressor :builtin
  
          # Specify sources for assets
          #
          sources &lt;&lt; [
            'assets'
          ]
        end
  </code></pre>