Check todoist due date is not None in async_get_events (#36140)

* Check that due date is not None

Check that due date is not None, prevents taks without due dates from breaking Calendar API

* Invert None check to reduce indentation

homeassistant/components/todoist/calendar.py

@@ -500,6 +500,8 @@ class TodoistProjectData:
 
         events = []
         for task in project_task_data:
+            if task["due"] is None:
+                continue
             due_date = _parse_due_date(task["due"])
             if start_date < due_date < end_date:
                 event = {