Fix default handling with newer voluptious

It seems newer voluptuous passes the specified default value into the
verification method. Previously if data wasn't supplied it seems to have
not validated anything and returend the default. Anyway this means we
need to use a default value that matches our input type and manipulate
it on the output end the same way we would normal input.

We make this update in order to use newer voluptuous which will be
required when we switch to python3.10.

Change-Id: I64d9c8ac1334971f2d1c82f19ea675022635dc37

grafana_dashboards/schema/template/__init__.py

@@ -25,20 +25,18 @@ from grafana_dashboards.schema.template.query import Query
 class Template(object):
 
     def __init__(self):
-        # TODO(pabelanger): This is pretty ugly, there much be a better way to
+        self.defaults = []
-        # set default values.
-        self.defaults = {
-            'enabled': False,
-            'list': [],
-        }
 
     def _validate(self):
 
         def f(data):
-            res = self.defaults
             if not isinstance(data, list):
                 raise v.Invalid('Should be a list')
 
+            res = {
+                'enabled': False,
+                'list': []
+            }
             for template in data:
                 res['enabled'] = True
                 validate = Base().get_schema()

requirements.txt

@@ -4,4 +4,4 @@ python-slugify
 PyYAML>=3.1.0
 requests
 six>=1.6.0
-voluptuous<=0.10.5
+voluptuous>0.10.5