setuptools 5.4.2

Applies setuptools 5.4.2 to three formulas. I’ve excluded Python3 for
now because setuptools & pip’s manual install was previous removed in
[this](https://github.com/Homebrew/homebrew/pull/27636) PR, and I don’t
want to reinstate something that Jack previously okayed the removal of
without knowing that it is okay to do so.
pypy: add 2.3.1 bottle.
pypy3: add 2.3.1 bottle.
python: update 2.7.8 bottle.