Configure tox-gh-actions

tox.ini

@@ -2,6 +2,14 @@
 isolated_build = True
 envlist = python
 
+[gh-actions]
+python =
+    3.5: python
+    3.6: python
+    3.7: python
+    3.8: python
+    3.9: python
+
 [testenv]
 deps = pytest
        pytest-cov