title: activated python venv but installs globally
body: <pre><code>pip3 list | grep unicorn
  </code></pre>
  <p>returns no results</p>
  <pre><code>source ~/scripts/venv/unicorn-hat-sim/bin/activate
  </code></pre>
  <p>prompt changes to show venv is activated</p>
  <pre><code>pip3 install unicorn-hat-sim
  pip3 list | grep unicorn
  unicorn-hat-sim   1.0.0
  pip3 show unicorn-hat-sim
  Name: unicorn-hat-sim
  Version: 1.0.0
  Summary: Unicorn HAT (HD) simulator - Originally by Jannis Hermanns &lt;jannis@gmail.com&gt;
  Home-page: https://github.com/mapitman/unicorn-hat-sim
  Author: Mark Pitman
  Author-email: mark.pitman@gmail.com
  License: MIT
  Location: /home/rossgoodmancom/.local/lib/python3.7/site-packages
  Requires: pygame
  Required-by: 
  </code></pre>
  <p>As you can see it has been installed in the .local/lib rather than in the venv
  I confirmed this by</p>
  <pre><code>deactivate
  pip3 list | grep unicorn
  unicorn-hat-sim   1.0.0  
  </code></pre>
  <p>What am I doing wrong?</p>