Update shell.nix and use django-types

shell.nix

@@ -1,5 +1,29 @@
 { pkgs ? import <nixpkgs> { }, ... }:
 
+let
+  python = pkgs.python38;
+
+  django-types = python.pkgs.buildPythonPackage rec {
+    pname = "django-types";
+    version = "0.17.0";
+
+    format = "pyproject";
+
+    src = pkgs.fetchPypi {
+      inherit pname version;
+      hash = "sha256-wcQqt4h2xXxyg0LVqwYHJas3H8jcg7uFuuC+BoRqrXA=";
+    };
+
+    nativeBuildInputs = with python.pkgs; [ poetry-core ];
+
+    # setup.cfg tries to pull in nonexistent LICENSE.txt file
+    # postPatch = "rm setup.cfg";
+
+    # propagatedBuildInputs = [ django typing-extensions ];
+  };
+in
+
+
 pkgs.mkShell {
   shellHook = ''
     export DJANGO_SETTINGS_MODULE=gestioasso.settings.local
@@ -10,12 +34,11 @@ pkgs.mkShell {
     pip install -r requirements-devel.txt | grep -v 'Requirement already satisfied:'
   '';
 
-  packages = with pkgs; [
-    python38
-    python38Packages.pip
-    python38Packages.virtualenv
-    python38Packages.python-ldap
-  ];
+  packages = [ python django-types ] ++ (with python.pkgs; [
+    pip
+    virtualenv
+    python-ldap
+  ]);
 
   allowSubstitutes = false;
 }