python3: iterate on keys copy

hreports/settings.py

@@ -107,7 +107,8 @@ __settings['REPORTS_DEFAULT'] = {
         'title': 'Trésorerie'
     },
 }
-for report_type in __settings['REPORTS_DEFAULT'].keys():
+
+for report_type in list(__settings['REPORTS_DEFAULT']):
     if report_type in __reports_default:
         import collections
         def update(d, u):