Changed minversion in tox to 3.18.0

The patch bumps min version of tox to 3.18.0 in order to
replace tox's whitelist_externals by allowlist_externals option:
https://github.com/tox-dev/tox/blob/master/docs/changelog.rst#v3180-2020-07-23

Change-Id: I75d9aa9aafc692f7bc67be59ee20523eb07d573d

1 files changed, 2 insertions, 2 deletions

diff --git a/tox.ini b/tox.ini
index 9b66168..2ec0dad 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-minversion = 3.1.1
+minversion = 3.18.0
 envlist = py3,pep8
 ignore_basepython_conflict = true
 
@@ -23,7 +23,7 @@ commands =
 commands = {posargs}
 
 [testenv:docs]
-whitelist_externals =
+allowlist_externals =
   rm
 deps =
   {[testenv]deps}