use allowlist_externals instead of whitelist_externals (#40)

`whitelist_externals` is now deprecated, use `allowlist_externals`
instead.

See: https://tox.wiki/en/latest/config.html#conf-allowlist_externals
Signed-off-by: Daniel Ziegenberg <daniel@ziegenberg.at>

Author: ziegenberg

tox.ini

@@ -44,7 +44,7 @@ passenv =
     SSL_CERT_FILE
     TOXENV
     TWINE_*
-whitelist_externals =
+allowlist_externals =
     bash
     twine
     pytest
@@ -97,7 +97,7 @@ passenv =
     TWINE_*
     MOLECULE_*
     OS_*
-whitelist_externals =
+allowlist_externals =
     bash
     twine
     pytest