Title: #867: ci: use python2 version of pytest
Fedora 31 changed symlink of /usr/bin/py.test from pytest2 to pytest3.
We need to run the python2 version in order to run our tests with python2.
We might want to switch to Python3 in the future, but this is a quick fix
for current situation when we cannot test against rawhide.
To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/867/head:pr867
git checkout pr867