test kombu 5.3.0 & minor doc update. 
====================================
 ``celery.worker.pidbox``
====================================

.. contents::
    :local:
.. currentmodule:: celery.worker.pidbox

.. automodule:: celery.worker.pidbox
    :members:
    :undoc-members:

====================================
 ``celery.worker.pidbox``
====================================

.. contents::
    :local:
.. currentmodule:: celery.worker.pidbox

.. automodule:: celery.worker.pidbox
    :members:
    :undoc-members:
