tox: fix checkqa envlist entries (pytest-dev#525)

Author: blueyed

tox.ini

@@ -8,7 +8,7 @@ envlist =
  - pypy3-pytest3-django1.8-{sqlite,sqlite_file}
  - pypy3-pytest2-django1.8-sqlite_file
  - pypy-pytest3-django1.10-sqlite_file
- - py{35,py27}-checkqa
+ - py{36,27}-checkqa
 
 [testenv]
 deps =