Fix flake8 targets in tox config

Author: webknjaz

tox.ini

@@ -22,7 +22,7 @@ commands=
 [testenv:flakes]
 changedir=
 deps = flake8
-commands = flake8 setup.py testing xdist
+commands = flake8 setup.py testing src/pytest_forked/
 
 [testenv:readme]
 changedir =