python310Packages.django: migrate to django_4

3.2 LTS ran out of mainstream support in 2021/12 and we should probably
stay on the latest LTS release, that receives mainstream support.

nixos/doc/manual/release-notes/rl-2311.section.md

@@ -158,6 +158,18 @@ The module update takes care of the new config syntax and the data itself (user
 
 ## Nixpkgs internals {#sec-release-23.11-nixpkgs-internals}
 
+- The `django` alias in the python package set was upgraded to Django 4.x.
+  Applications that consume Django should always pin their python environment
+  to a compatible major version, so they can move at their own pace.
+
+  ```nix
+  python = python3.override {
+    packageOverrides = self: super: {
+      django = super.django_3;
+    };
+  };
+  ```
+
 - The `qemu-vm.nix` module by default now identifies block devices via
   persistent names available in `/dev/disk/by-*`. Because the rootDevice is
   identfied by its filesystem label, it needs to be formatted before the VM is

pkgs/top-level/python-packages.nix

@@ -2727,12 +2727,11 @@ self: super: with self; {
 
   distutils_extra = callPackage ../development/python-modules/distutils_extra { };
 
-  django = self.django_3;
-
-  # Current LTS
+  # LTS in extended support phase
   django_3 = callPackage ../development/python-modules/django/3.nix { };
 
-  # Current latest
+  # LTS with mainsteam support
+  django = self.django_4;
   django_4 = callPackage ../development/python-modules/django/4.nix { };
 
   django-admin-datta = callPackage ../development/python-modules/django-admin-datta { };