Remove pypy3

Author: dlai286

.travis.yml

@@ -9,7 +9,6 @@ env:
   - TOX_ENV=py34
   - TOX_ENV=py35
   - TOX_ENV=pypy
-  - TOX_ENV=pypy3
   - TOX_ENV=coverage
 
 # command to install dependencies, e.g. pip install -r requirements.txt --use-mirrors