Added more verbose output for pytest in tox.ini file

Signed-off-by: Grzegorz Latosinski <glatosinski@antmicro.com>

tox.ini

diff --git a/tox.ini b/tox.ini
index 7fcb0fc..ea11e92 100644
--- a/tox.ini
+++ b/tox.ini
@@ -22,7 +22,7 @@
     # use `python setup.py check -m -r -s` instead.
     python setup.py check -m -s
     flake8 .
-    pytest
+    pytest -vvvv
 [flake8]
 exclude = .tox,*.egg,build,data
 select = E,W,F