remove middleware outdated inheritance

backend/config/middleware.py

@@ -1,11 +1,13 @@
 """middleware"""
 
 from django.conf import settings
-from django.utils.deprecation import MiddlewareMixin
 
 
-class StartTimeMiddleware(MiddlewareMixin):
-    """add a start time header"""
+class StartTimeMiddleware:
+    """set start time header"""
+
+    def __init__(self, get_response):
+        self.get_response = get_response
 
     def __call__(self, request):
         response = self.get_response(request)