Revert "python3Packages.afdko: 3.9.0 -> 3.9.1"

This reverts commit 246216e.

3.9.1 does not compile due to patch collision:

       > applying patch /nix/store/sickncxw0s730j6gfrnlsi5ndgysi6la-libxml2-cmake-find-package.patch
       > patching file CMakeLists.txt
       > Hunk #1 FAILED at 42.

Fixing it is not trivial as upstream started bundling libxml2:
  #182941 (comment)

Let's revert the update for now.

pkgs/development/python-modules/afdko/default.nix

@@ -14,13 +14,13 @@
 
 buildPythonPackage rec {
   pname = "afdko";
-  version = "3.9.1";
+  version = "3.9.0";
 
   disabled = pythonOlder "3.7";
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "sha256-AtRNaZzn9BoNIjvKhS7rsYVfHw26JKKUFqO/6TcBIkw=";
+    sha256 = "1fjsaz6bp028fbmry6fzfcih78mdzycqmky1wsz5y0bg4kfk4shh";
   };
 
   format = "pyproject";