remove python 3.7 from tests. 
========================================
 ``celery.beat``
========================================

.. contents::
    :local:
.. currentmodule:: celery.beat

.. automodule:: celery.beat
    :members:
    :undoc-members:

========================================
 ``celery.beat``
========================================

.. contents::
    :local:
.. currentmodule:: celery.beat

.. automodule:: celery.beat
    :members:
    :undoc-members:
