Fixing tests with tox 4.2.6

Remove basepython from testenv

Change-Id: Idb2a9d9dcc5a73e15e5cbab165b2b629a8b26afe

Author: wchy1001

tox.ini

@@ -7,7 +7,6 @@ skipsdist = True
 ignore_basepython_conflict = True
 
 [testenv]
-basepython = python3
 setenv = VIRTUAL_ENV={envdir}
          NOSE_WITH_OPENSTACK=1
          NOSE_OPENSTACK_COLOR=1
@@ -48,6 +47,7 @@ commands =
 [testenv:docs]
 deps =
        -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+       -r{toxinidir}/requirements.txt
        -r{toxinidir}/doc/requirements.txt
 commands =
   rm -rf doc/html doc/build