python311Packages.simplefix: add changelog to meta

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

···
   meta = with lib; {
     description = "Simple FIX Protocol implementation for Python";
     homepage = "https://github.com/da4089/simplefix";
+    changelog = "https://github.com/da4089/simplefix/releases/tag/v${version}";
     license = licenses.mit;
     maintainers = with maintainers; [ catern ];
   };