patman: document how to run test suite via pytest

Pytest offers useful features such as selecting tests by means of a
regular expression, or running the pdb debugger upon encountering a
test failure.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Maxim Cournoyer <maxim.cournoyer@savoirfairelinux.com>
1 file changed