tox: Remove basepython and ineffective ignore_basepython_conflict

Change-Id: I57e28d243f7da65d7c86700d73b43212e468c29c
Signed-off-by: Ivan Anfimov <lazekteam@gmail.com>
diff --git a/tox.ini b/tox.ini
index c8add2c..21574f4 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,10 +1,8 @@
 [tox]
 minversion = 3.18.0
 envlist = pep8
-ignore_basepython_conflict = True
 
 [testenv]
-basepython = {env:TOX_PYTHON:python3}
 usedevelop = True
 setenv =
    VIRTUAL_ENV={envdir}