Disable pytest's logs reporting

CubicWeb already prints captured logs in stderr upon test failure, so we
get them twice. Until we fix our logging management, disabling pytest
capture and restore brings the output level back to sanity.

tox.ini

@@ -46,6 +46,7 @@ commands =
 
 [pytest]
 python_files = *test_*.py
+log_print = false
 
 [flake8]
 format = pylint