Add a dedicated py-test.mk for running tests with pytest instead of
python.
The commit introduces a new variable PYTHON_RUNNER, which is then
used by py-run.mk to do it's usual thing. Running pytest is similar
enough to running Python programs to keep the rest of the machinery
and prevent redundancy from creeping in.
Signed-off-by: Jan Lindemann <jan@janware.com>
Jan Lindemann
52f34a915d