[REFACTOR] change user group creation to get_or_create

authentication/managers.py

@@ -18,12 +18,8 @@ class CustomUserManager(BaseUserManager):
         user = self.model(email=email, **extra_fields)
         user.set_password(password)
         user.save()
-        if not Group.objects.filter(name='client').exists():
-            client_role = Group.objects.create(name='client')
-            user.groups.add(client_role)
-        else:
-            client_role = Group.objects.get(name='client')
-            user.groups.add(client_role)
+        client_role, _created = Group.objects.get_or_create(name='client')
+        user.groups.add(client_role)
         return user
 
     def create_superuser(self, email, password, **extra_fields):