Retain available Python versions

Author: Kroisse

.travis.yml

@@ -3,18 +3,13 @@ dist: xenial
 os: linux
 language: python
 python:
-- 'pypy-5.4'
-- 'pypy2.7-5.10'
-- 'pypy3.5-5.10'
-- 'pypy2.7-6.0'
-- 'pypy3.5-6.0'
-- 'pypy2.7-7.1'
-- 'pypy3.5-7.1'
-- '2.7'
-- '3.4'
-- '3.5'
-- '3.6'
 - '3.7'
+- '3.6'
+- '3.5'
+- '3.4'
+- '2.7'
+- 'pypy3.5-6.0'
+- 'pypy2.7-6.0'
 matrix:
   include:
   - os: osx