core: bump django-rest-framework from 3.14.0 to 3.16.0 (#14057)

upgrade `django-rest-framework` to `3.16.0`

The reverted commit is purely an optimization which unfortunately breaks authentik, specifically Blueprints. It adds `getattr(serializer.instance, field)` to a validator. If `field` is a `RelatedObject`, that invocation queries the database.

When authentik creates objects using Blueprints, it doesn't place related objects into the database before the validator tries to get them from there, so with the reverted commit, it produces `RelatedObjectDoesNotExist`.

Perhaps a long-term solution is to revise how Blueprints work, or perhaps it is to change upstream. But in the meantime, Django 5.0 support ended and upgrading to Django 5.1 requires an upgrade of `django-rest-framework` to `3.16.0`, hence this workaround.

See
- encode/django-rest-framework#9154
- encode/django-rest-framework#9358
- encode/django-rest-framework#9482
- encode/django-rest-framework#9483

Author: gergosimonyi

pyproject.toml

@@ -24,7 +24,7 @@ dependencies = [
     "django-redis",
     "django-storages[s3]",
     "django-tenants",
-    "djangorestframework ==3.14.0",
+    "djangorestframework",
     "djangorestframework-guardian",
     "docker",
     "drf-orjson-renderer",
@@ -104,6 +104,7 @@ dev = [
 [tool.uv.sources]
 django-tenants = { git = "https://github.com/rissson/django-tenants.git", branch = "authentik-fixes" }
 opencontainers = { git = "https://github.com/BeryJu/oci-python", rev = "c791b19056769cd67957322806809ab70f5bead8" }
+djangorestframework = { git = "https://github.com/authentik-community/django-rest-framework", rev = "896722bab969fabc74a08b827da59409cf9f1a4e" }
 
 [project.scripts]
 ak = "lifecycle.ak:main"