tox: Trivial cleanup

move 'basepython' to the top-level 'testenv'

Change-Id: Ic3474388671341921bbfe3267405b4d90412ace0

tox.ini

@@ -1,9 +1,10 @@
 [tox]
-minversion = 2.0
+minversion = 3.1
 envlist = py27,py37,pep8
+ignore_basepython_conflict = True
 
 [testenv]
-install_command = pip install {opts} {packages}
+basepython = python3
 whitelist_externals =
   find
 deps =
@@ -13,18 +14,15 @@ deps =
 commands = stestr run --slowest {posargs}
 
 [testenv:pep8]
-basepython = python3
 commands =
   flake8
   # Run security linter
   bandit -r oslo_vmware
 
 [testenv:bandit]
-basepython = python3
 commands = bandit -r oslo_vmware
 
 [testenv:docs]
-basepython = python3
 whitelist_externals =
   rm
 deps =
@@ -35,7 +33,6 @@ commands =
   sphinx-build -W --keep-going -b html doc/source doc/build/html
 
 [testenv:cover]
-basepython = python3
 commands =
   coverage erase
   find . -type f -name "*.pyc" -delete
@@ -43,7 +40,6 @@ commands =
   coverage report
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [flake8]
@@ -58,7 +54,6 @@ import_exceptions =
 local-check-factory = oslo_vmware.hacking.checks.factory
 
 [testenv:releasenotes]
-basepython = python3
 whitelist_externals = rm
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
@@ -68,7 +63,6 @@ commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees --keep-going -b html releasenotes/source releasenotes/build/html
 
 [testenv:bindep]
-basepython = python3
 # Do not install any requirements. We want this to be fast and work even if
 # system dependencies are missing, since it's used to tell you what system
 # dependencies are missing! This also means that bindep must be installed
@@ -78,7 +72,6 @@ deps = bindep
 commands = bindep test
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt