исправил некоторые косяки

users/admin.py

@@ -1,3 +1,8 @@
 from django.contrib import admin
+from .models import User
 
-# Register your models here.
+
+@admin.register(User)
+class UserAdmin(admin.ModelAdmin):
+    list_display = ['id', 'login', 'is_superuser', 'registered', 'last_password_change']
+    readonly_fields = ['id', 'registered']