Add required param `renderer` to Widget.render

Added on Django 1.11 and required since 2.1
The renderer argument is added to the Widget.render() method.
https://docs.djangoproject.com/en/2.1/releases/1.11/#id2

orchestra/forms/widgets.py

@@ -18,8 +18,8 @@ class SpanWidget(forms.Widget):
         self.display = kwargs.pop('display', None)
         super(SpanWidget, self).__init__(*args, **kwargs)
 
-    def render(self, name, value, attrs=None):
-        final_attrs = self.build_attrs(attrs, name=name)
+    def render(self, name, value, attrs=None, renderer=None):
+        final_attrs = self.build_attrs(attrs, extra_attrs={'name':name})
         original = self.original or value
         display = original if self.display is None else self.display
         # Display icon