PLT-6108 fixing to use senderId for push (#6245)

model/push_notification.go

@@ -36,7 +36,7 @@ type PushNotification struct {
 	ChannelId        string `json:"channel_id"`
 	ChannelName      string `json:"channel_name"`
 	Type             string `json:"type"`
-	UserId           string `json:"user_id"`
+	SenderId         string `json:"sender_id"`
 	OverrideUsername string `json:"override_username"`
 	OverrideIconUrl  string `json:"override_icon_url"`
 	FromWebhook      string `json:"from_webhook"`