[$] Leaving python-dev behind

It was not all that long ago that Python began its experiment withreplacing one of its mailing lists with a forum on its Discourse discussion site. Overtime, the Discourse instance has become more and more popular within thePython community. It would seem that another mailing list will soon besubsumed within Discourse as the Python steering council is planning toeffectively retire the venerable python-dev mailing list soon.