Use py3.7 for testing

docs/develop.rst

@@ -25,15 +25,15 @@ They get called by different ``mrbob hooks``, like ``pre_render``, ``post_render
 
 
 Standalone templates
-=====================
+====================
 
 Standalone templates are normal templates for mrbob, which are meant to live standalone and are not depending on any other template.
 
 Examples are the ``buildout`` and ``addon`` templates. For details see the documentation of the mrbob package.
 
 
 Sub-templates
-============
+=============
 
 Sub-templates are templates which are living inside an existing package created by a standalone template like the ``addon`` template.
 These templates extend the existing standalone template structure by new features like a ``theme`` or a ``content_type``.

tox.ini

@@ -1,8 +1,8 @@
 [tox]
 envlist =
     lint-py27,
-    lint-py36,
-    py{27,36}-packagetests,
+    lint-py37,
+    py{27,37}-packagetests,
     py{27}-skeletontests-Plone-{4.3,5.0,5.1}-template-addon
     py{27}-skeletontests-Plone-{4.3,5.0,5.1}-template-addon_content_type
     py{36}-skeletontests-Plone-{5.2}-template-addon_content_type
@@ -27,7 +27,7 @@ extras =
 
 basepython:
     py27: python2.7
-    py36: python3.6
+    py37: python3.7
 #    pypy: pypy
 
 commands =
@@ -148,8 +148,8 @@ deps = {[lint]deps}
 commands = {[lint]commands}
 whitelist_externals = {[lint]whitelist_externals}
 
-[testenv:lint-py36]
-basepython = python3.6
+[testenv:lint-py37]
+basepython = python3.7
 skip_install = true
 deps = {[lint]deps}
 commands = {[lint]commands}