⬆️(back) upgrade django to version 5.2

Django 5.2 is now mature enough and we can use it in production.
In some tests the number of sql queries is increasing. This is because
the `full_clean` method called in the `save` method on all our models is
creating a transaction, so a savepoint and release is added.
We also fix deprecated warning in this commit.

src/backend/core/migrations/0001_initial.py

@@ -504,7 +504,7 @@ class Migration(migrations.Migration):
         migrations.AddConstraint(
             model_name="documentaccess",
             constraint=models.CheckConstraint(
-                check=models.Q(
+                condition=models.Q(
                     models.Q(("team", ""), ("user__isnull", False)),
                     models.Q(("team__gt", ""), ("user__isnull", True)),
                     _connector="OR",
@@ -540,7 +540,7 @@ class Migration(migrations.Migration):
         migrations.AddConstraint(
             model_name="templateaccess",
             constraint=models.CheckConstraint(
-                check=models.Q(
+                condition=models.Q(
                     models.Q(("team", ""), ("user__isnull", False)),
                     models.Q(("team__gt", ""), ("user__isnull", True)),
                     _connector="OR",