[backend][views] Fix key search in dictionary

beat/web/backend/views.py

@@ -77,7 +77,7 @@ def scheduler(request):
     cache_gb = int(cache['capacity-in-megabytes'] / 1024.0)
 
     refreshing_period = getattr(settings, 'SCHEDULING_INTERVAL', 5)
-    if request.GET.has_key('period'):
+    if 'period' in request.GET:
         refreshing_period = int(request.GET['period'])
 
     return render(request,