Merge branch 'update-tox' into 'master'

Update tox.ini. Advances AlekSIS-Core#338

See merge request !119

tox.ini

@@ -10,6 +10,8 @@ skip_install = true
 envdir = {toxworkdir}/globalenv
 commands_pre =
      - poetry install
+     - poetry run aleksis-admin yarn install
+     - poetry run aleksis-admin collectstatic --no-input
 commands =
     - poetry run pytest --cov=. {posargs} aleksis/