Changes:

• Uses get_current_context() instead of **kwargs to get context inside of tasks (closes Refactor task_groups to use airflow's get_current_context() func #217 )
  • removes several discovered vestigial uses of removed keyword-args from task invocations.
• Switches to preferring use of a key (rather than a task_id) for accessing xcom objects
• Replaces dt.datetime.utcnow() instances with dt.datetime.now(dt.UTC) (closes Replace datetime.datetime.utcnow() with datetime.datetime.now(datetime.UTC) (deprecation incoming #218)
• Adds new datasets (that were used to test the refactored taskflows)
• Fixes a number of bugs in dbt models discovered while materializing clean stage models into tables