Update Ubuntu Bionic to Focal in setup.rst (#654)

* Update Ubuntu Bionic to Focal in setup.rst

Ubuntu Focal Fossa is the latest LTS release. Its default Python version is 3.8.

Also, I added a numeric version of the Ubuntu release because it is likely more familiar to users.

* Update setup docs to Jammy Jellyfish.

Co-authored-by: Ezio Melotti <ezio.melotti@gmail.com>

Author: illia-v

setup.rst

@@ -315,9 +315,9 @@ dependencies for the Python you're working on by using the ``apt`` command.
 First, make sure you have enabled the source packages in the sources list.
 You can do this by adding the location of the source packages, including
 URL, distribution name and component name, to ``/etc/apt/sources.list``.
-Take Ubuntu Bionic for example::
+Take Ubuntu 22.04 LTS (Jammy Jellyfish) for example::
 
-   deb-src http://archive.ubuntu.com/ubuntu/ bionic main
+   deb-src http://archive.ubuntu.com/ubuntu/ jammy main
 
 For other distributions, like Debian, change the URL and names to correspond
 with the specific distribution.