docs: remove references to EoL software

Debian buster EoL since 2022-09-10

docs/source/install.rst

@@ -96,68 +96,42 @@ advantages:
   rolled back in case of incompatibility. The package can also be purged
   entirely from the system in seconds.
 
-stable ("buster")
-------------------
+stable (as of 2024, "bookworm")
+-------------------------------
 
-The version of Gunicorn in the Debian_ "stable" distribution is 19.9.0
-(December 2020). You can install it using::
+The version of Gunicorn in the Debian_ "stable" distribution is 20.1.0
+(2021-04-28). You can install it using::
 
-    $ sudo apt-get install gunicorn3
-
-You can also use the most recent version 20.0.4 (December 2020) by using
-`Debian Backports`_. First, copy the following line to your
-``/etc/apt/sources.list``::
-
-    deb http://ftp.debian.org/debian buster-backports main
-
-Then, update your local package lists::
-
-    $ sudo apt-get update
-
-You can then install the latest version using::
-
-    $ sudo apt-get -t buster-backports install gunicorn
-
-oldstable ("stretch")
----------------------
-
-While Debian releases newer than Stretch will give you gunicorn with Python 3
-support no matter if you install the gunicorn or gunicorn3 package for Stretch
-you specifically have to install gunicorn3 to get Python 3 support.
-
-The version of Gunicorn in the Debian_ "oldstable" distribution is 19.6.0
-(December 2020). You can install it using::
-
-    $ sudo apt-get install gunicorn3
+    $ sudo apt-get install gunicorn
 
-You can also use the most recent version 19.7.1 (December 2020) by using
+You may have access to a more recent packaged version by using
 `Debian Backports`_. First, copy the following line to your
 ``/etc/apt/sources.list``::
 
-    deb http://ftp.debian.org/debian stretch-backports main
+    deb http://ftp.debian.org/debian bookworm-backports main
 
 Then, update your local package lists::
 
     $ sudo apt-get update
 
-You can then install the latest version using::
+You can then install the latest available version using::
 
-    $ sudo apt-get -t stretch-backports install gunicorn3
+    $ sudo apt-get -t bookworm-backports install gunicorn
 
-Testing ("bullseye") / Unstable ("sid")
----------------------------------------
+Testing (as of 2024, "trixie") / Unstable ("sid")
+-------------------------------------------------
 
-"bullseye" and "sid" contain the latest released version of Gunicorn 20.0.4
-(December 2020). You can install it in the usual way::
+"trixie" and "sid" ship the most recently packaged version of Gunicorn 20.1.0
+(2021-04-28). You can install it in the usual way::
 
     $ sudo apt-get install gunicorn
 
 
 Ubuntu
 ======
 
-Ubuntu_ 20.04 LTS (Focal Fossa) or later contains the Gunicorn package by
-default 20.0.4 (December 2020) so that you can install it in the usual way::
+Ubuntu_ 20.04 LTS (Focal Fossa) and later ship packages similar to Debian
+so that you can install it in the usual way::
 
     $ sudo apt-get update
     $ sudo apt-get install gunicorn