Only test twisted on 3.7 (latest minor) (#428)

Signed-off-by: Xavier Fernandez <[email protected]>

Author: xavfernandez

tox.ini

@@ -29,7 +29,7 @@ deps =
 [testenv]
 deps =
     {[base]deps}
-    {py27,py34,py35,py36,pypy,pypy3}: twisted
+    {py27,py37,pypy,pypy3}: twisted
 commands = coverage run --parallel -m pytest {posargs}
 
 ; Ensure test suite passes if no optional dependencies are present.