improvement: add to tox for test different environments

Author: leafcoder

tox.ini

@@ -0,0 +1,23 @@
+[tox]
+envlist =
+    py{35,36,37}-django{20,21,22}
+
+[testenv]
+deps=
+    django20: Django>=2.0,<2.1
+    django21: Django>=2.1,<2.2
+    django22: Django>=2.2,<2.3
+    django_mysql
+    django-cors-headers
+    django-crontab
+    django-filter
+    djangorestframework
+    Scrapy
+    scrapy-djangoitem
+setenv=
+    PYTHONDONTWRITEBYTECODE=1
+changedir=
+    demo_proj
+commands=
+    {envpython} manage.py test django_covid19
+sitepackages=False