title: How can I specify library versions in setup.py?
body: <p>In my <code>setup.py</code> file, I've specified a few libraries needed to run my project:</p>
  
  <pre><code>setup(
      # ...
      install_requires = [
          'django-pipeline',
          'south'
      ]
  )
  </code></pre>
  
  <p>How can I specify required versions of these libraries? </p>