There are a few changes that need to happen together with this one,
namely we need to specify explicit 3.7+ PyPy3 versions and in order
to do that we have to upgrade the setup-python GH action.
from __future__ annotations are the default on Python 3.10 so the tricks
we used to keep the test suite nice can no longer be applied.
CI addition to make sure it stays compatible.
Free Travis CI is shutting down and since I already have Codecov set up
in other projects instead of Coveralls I'm switching that too for
consistency.
There's no nightly so I left it out for now.
Jakub Stasiak