add unique for endpoint and date time filed and added aud for model

backend/account/models.py

@@ -144,9 +144,9 @@ from pywebpush import webpush, WebPushException
 
 class PushSubscription(models.Model):
     user = models.ForeignKey(User, on_delete=models.CASCADE)
-    endpoint = models.TextField()
+    endpoint = models.TextField(unique=True)
     keys = models.JSONField()
-    created_at = models.DateField(auto_now_add=True)
+    created_at = models.DateTimeField(auto_now_add=True)
 
     def __str__(self):
         return f'{self.user} push'
@@ -192,7 +192,8 @@ class PushSubscription(models.Model):
                     data=json.dumps(payload),
                     vapid_private_key=settings.VAPID_PRIVATE_KEY,
                     vapid_claims={
-                        "sub": "mailto:admin@example.com"
+                        "sub": "mailto:admin@example.com",
+                        'aud': 'https://mamalizz-cooked.vercel.app'
                     }
                 )
             except WebPushException as ex: