python3: replace has_key usage (#38094)

auquotidien/modules/template.py

@@ -16,7 +16,7 @@ def get_decorate_vars(body, response, generate_breadcrumb=True, template_context
         template_context['form_side'] = template_context['form_side']()
 
     for key in ('bigdiv', 'gauche'):
-        if not response.filter.has_key(key):
+        if not key in response.filter:
             response.filter[key] = None
 
     return wcs_get_decorate_vars(body, response, generate_breadcrumb)