[skeleton] Drop py27 tox environment
Since we dropped py2 support from cubicweb, it does not make
much sense to keep it in skeleton from now on.
--- a/cubicweb/skeleton/tox.ini.tmpl Wed Apr 17 15:30:42 2019 +0200
+++ b/cubicweb/skeleton/tox.ini.tmpl Wed Apr 17 16:41:41 2019 +0200
@@ -1,5 +1,5 @@
[tox]
-envlist = py27,py3,flake8,check-manifest
+envlist = py3,flake8,check-manifest
[testenv]
deps =