tox.ini: add py3 run (#41302)

tox.ini

@@ -1,28 +1,35 @@
 [tox]
-envlist = coverage-dj111-pylint
+envlist = py27-coverage-dj111,py3-coverage-{dj111,dj22}
 toxworkdir = {env:TMPDIR:/tmp}/tox-{env:USER}/petale/
 
 [testenv]
 usedevelop=True
-basepython = python2
 setenv =
   DJANGO_SETTINGS_MODULE=petale.settings
   PETALE_SETTINGS_FILE=tests/settings.py
   coverage: COVERAGE=--junitxml=test_results.xml --cov-report xml --cov-report html --cov=petale/ --cov-config .coveragerc
 deps =
-  dj18: django>=1.8,<1.9
-  dj111: django>=1.11,<1.12
+  dj111: django>=1.11,<2
+  dj22: django>=2.2,<2.3
   pytest-cov
-  pytest-django<3.4.6
+  pytest-django
   pytest
   pylint<1.8
   pylint-django<0.8.1
   mock
   django-webtest<1.9.3
-  dj18: djangorestframework<3.4
   psycopg2
   pyquery
 commands =
   python setup.py compile_translations
   py.test {env:COVERAGE:} {posargs:tests/}
-  pylint: ./pylint.sh petale/
+
+[testenv:pylint]
+deps =
+    pylint<1.8
+    pylint-django<0.8.1
+commands =
+    /bin/bash -c "./pylint.sh petale/"
+
+[pytest]
+junit_family=xunit2