fix auth redirect

lectures/views.py

@@ -142,7 +142,7 @@ def view_group_lectures(request, group_id: int):
         if not group_id_exists:  # Doesn't exist at all
             raise HTTPExceptions.NOT_FOUND
         elif group_id_exists:  # Exists without permissions checks
-            if request.user_is_authenticated:  # The user is logged in
+            if request.user.is_authenticated:  # The user is logged in
                 raise HTTPExceptions.NOT_FOUND
             else:  # The user can log in
                 return generate_auth_redirect(request)