title: pytz package: can only be run with python2 (after pip install pytz) even though python3 is normally used
body: <p>When installing pytz to be used in a Python project, I get following Terminal output on my wsl Terminal:</p>
  
  <pre><code>pip install pytz
  DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. A future version of pip will drop support for Python 2.7. 
  More details about Python 2 support in pip, can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support
  Defaulting to user installation because normal site-packages is not writeable
  Collecting pytz
    Downloading pytz-2019.3-py2.py3-none-any.whl (509 kB)
       |████████████████████████████████| 509 kB 1.3 MB/s
  Installing collected packages: pytz
  Successfully installed pytz-2019.3
  </code></pre>
  
  <p>Afterwards, when running test.py I still got the error:</p>
  
  <pre><code>Traceback (most recent call last):   
    File "test.py", line 2, in &lt;module&gt;
      import pytz
  ModuleNotFoundError: No module named 'pytz'
  </code></pre>
  
  <p>Trying <code>import pytz-2019.3</code> and <code>pytz2019.3</code> threw SyntaxErrors.</p>
  
  <p>Finally, I could run the file with: <code>python2 test.py</code>. </p>
  
  <p>I am wondering (for this package and for other packages which yield to similar problems) how I could run it normally with <code>python3 test.py</code>. Would I need to change anything in the installation?</p>
  
  <p>Just for reference, this is the code I wanted to use:</p>
  
  <pre><code>from datetime import datetime
  import pytz
  tz_NY = pytz.timezone('America/New_York') 
  datetime_NY = datetime.now(tz_NY)
  print("NY time:", datetime_NY.strftime("%H:%M:%S"))
  </code></pre>
  
  <p>Thanks for your help!</p>