fix(tox): add new tox setup for github actions

tox.ini

@@ -1,22 +1,37 @@
 [tox]
-envlist = py{36}-django{111,20,21,22}-wagtail{20,21,22,23,24,25,26,211}{,-geoip2},lint
+envlist =
+    flake8
+    py{36,37,38}-dj{22}-wt{25,26,27,28,29,210,211,212,213}
+    py{37,38}-dj{30,31}-wt{28,29,210,211,212,213}
+
+[gh-actions]
+python =
+    3.6: py36
+    3.7: py37
+    3.8: py38
 
 [testenv]
-basepython = python3.6
+basepython =
+    py36: python3.6
+    py37: python3.7
+    py38: python3.8
 commands = coverage run --parallel -m pytest -rs {posargs}
 extras = test
 deps =
-    django20: django>=2.0,<2.1
+    dj22: Django>=2.2.8,<2.3
-    django21: django>=2.1,<2.2
+    dj30: Django>=3.0,<3.1
-    django22: django>=2.2,<2.3
+    dj31: Django>=3.1,<3.2
-    wagtail20: wagtail>=2.0,<2.1
+    wt23: wagtail>=2.3,<2.4
-    wagtail21: wagtail>=2.1,<2.2
+    wt24: wagtail>=2.4,<2.5
-    wagtail22: wagtail>=2.2,<2.3
+    wt25: wagtail>=2.5,<2.6
-    wagtail23: wagtail>=2.3,<2.4
+    wt26: wagtail>=2.6,<2.7
-    wagtail24: wagtail>=2.4,<2.5
+    wt27: wagtail>=2.7,<2.8
-    wagtail25: wagtail>=2.5,<2.6
+    wt28: wagtail>=2.8,<2.9
-    wagtail26: wagtail>=2.6,<2.7
+    wt29: wagtail>=2.9,<2.10
-    wagtail211: wagtail>=2.11,<2.12
+    wt210: wagtail>=2.10,<2.11
+    wt211: wagtail>=2.11,<2.12
+    wt212: wagtail>=2.12,<2.13
+    wt213: wagtail>=2.13,<2.14
     geoip2: geoip2
     django111: django>=1.11,<1.12
 
@@ -34,3 +49,12 @@ deps = flake8==3.5.0
 commands =
     flake8 src tests setup.py
     isort -q --recursive --diff src/ tests/
+
+[testenv:format]
+basepython = python3.8
+deps =
+    isort
+    black
+skip_install = true
+commands =
+    black --check setup.py wagtailstreamforms/ tests/