title: Can't install pip with get-pip, zipimport.ZipImportError: can't decompress data; zlib not available
body: <p>I'm trying to install fastapi on my ubuntu machine (20.04)
  This PC has Python 2, Python3 (pointing to Python3.8) and Python3.9 installed.</p>
  <p>If I try a pip3 install, it installs under Python3.8
  I've seen a trick, using <code>python3.9 -m pip3 ...</code> but Python3.9 doesn't have the module pip or pip3.</p>
  <p>I tried to install this using the get-pip.py trick, but it says there is no zlib.
  I then tried to install that using a few methods, the <code>sudo apt-get zlib1g-dev</code> method (which installs but doesn't fix the iussue) as well as one where you download zlib and ./configure and make it, which also appears to work but doesn't.</p>
  <p>A lot of solutions suggest using yum, but there's no yum package - sudo apt-get install yum doesn't work, and it's not on the ubuntu package manager site.</p>
  <p>I tried many things, but nothing worked so far.</p>
  <p>Either I need to get zlib to work, or I need to get the existing pip packaged to point to 3.9
  I suppose I could just use venvs (which <em>is</em> installed for 3.9, somehow, even though pip isn't! ) or I could just use 3.8 instead, but these are both workarounds.</p>
  <p>What do, Stack Overflow?</p>