Fix django default appconfig deprecation warning

[merwok]

fixes #140

[merwok]

Forgot that keeping forks in sync with github is not convenient — pulled and merged upstream.

I’ll rebase or you’ll squash merge!

[fabiocaccamo]

Is it safe to remove this also for older django versions?

I would keep it if django.version < 4 to be 101% backward compatible.

[merwok]

I’m not fully sure, would need a test project with these versions. The worst case is that they would have to have 'admin_interface.apps.AdminInterfaceConfig' in INSTALLED_APPS instead of 'admin_interface' alone.

---

On the topic of supported versions, I also wanted to ask you how you would feel about reducing them!
Keeping 4 older python versions and 4 django versions (LTS or current):

diff --git a/tox.ini b/tox.ini
--- a/tox.ini
+++ b/tox.ini
@@ -1,35 +1,28 @@
 [tox]
 envlist =
-    py27-{dj17,dj18,dj19,dj110,dj111}-{sqlite,postgres},
-    py35-{dj18,dj19,dj110,dj111,dj20,dj21,dj22}-{sqlite,postgres},
-    py36-{dj18,dj19,dj110,dj111,dj20,dj21,dj22,dj30,dj31,dj32,djmaster}-{sqlite,postgres},
-    py37-{dj20,dj21,dj22,dj30,dj31,dj32,djmaster}-{sqlite,postgres},
-    py38-{dj22,dj30,dj31,dj32,djmaster}-{sqlite,postgres},
-    py39-{dj22,dj30,dj31,dj32,djmaster}-{sqlite,postgres},
+    py27-dj111-{sqlite,postgres},
+    py36-{dj22,dj31,dj32,djmaster}-{sqlite,postgres},
+    py37-{dj22,dj31,dj32,djmaster}-{sqlite,postgres},
+    py38-{dj22,dj31,dj32,djmaster}-{sqlite,postgres},
+    py39-{dj22,dj31,dj32,djmaster}-{sqlite,postgres},
+    py310-{dj22,dj31,dj32,djmaster}-{sqlite,postgres},

[fabiocaccamo]

I use this library on some very old projects and I like to update it to the latest version to use new features.