Remove Python2 'next' assignment in scheduler (#932)

* Remove Python2 'next' assignment in scheduler

Remove unnecessary compatibility code for legacy Python 2 which is no longer supported.

* Use Python3 next

Author: cclauss

django_celery_beat/schedulers.py

@@ -167,15 +167,13 @@ def __next__(self):
         self.model.total_run_count += 1
         self.model.no_changes = True
         return self.__class__(self.model)
-    next = __next__  # for 2to3
 
     def save(self):
         # Object may not be synchronized, so only
         # change the fields we care about.
         obj = type(self.model)._default_manager.get(pk=self.model.pk)
         for field in self.save_fields:
             setattr(obj, field, getattr(self.model, field))
-
         obj.save()
 
     @classmethod

t/unit/test_schedulers.py

@@ -314,7 +314,7 @@ def test_entry(self):
         e2 = self.Entry(m2, app=self.app)
         assert e2.last_run_at is right_now
 
-        e3 = e2.next()
+        e3 = next(e2)
         assert e3.last_run_at > e2.last_run_at
         assert e3.total_run_count == 1