Inclusive jargon

Following stestr's example where arguments such as --blacklist-file,
--black-regex and --whitelist-file are deprecated since its
3.1.0 release, let's do the change here as well in order to
get tempest consumers some time for the transition.

This change deprecates the following arguments and replaces them
by new ones which are functionally equivavelnt:
* --black-regex is replaced by --exclude-regex
* --blacklist-file is replaced by --exclude-list
* --whitelist-file is replaced by --include-list

For now, Tempest will accept both (new and old) arguments to make
the transition smoother for all consumers.

The patch also 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: I3e09b31f63d2cd7ea41c48e62432bd3bc54fcf44
diff --git a/doc/source/stable_branch_support_policy.rst b/doc/source/stable_branch_support_policy.rst
index 87e3ad1..9c2d1ed 100644
--- a/doc/source/stable_branch_support_policy.rst
+++ b/doc/source/stable_branch_support_policy.rst
@@ -20,7 +20,7 @@
 testing branches in these phases, it's possible that we'll introduce changes to
 Tempest on master which will break support on *Extended Maintenance* phase
 branches. When this happens the expectation for those branches is to either
-switch to running Tempest from a tag with support for the branch, or blacklist
+switch to running Tempest from a tag with support for the branch, or exclude
 a newly introduced test (if that is the cause of the issue). Tempest will not
 be creating stable branches to support *Extended Maintenance* phase branches, as
 the burden is on the *Extended Maintenance* phase branche maintainers, not the Tempest