Fix of hexdigest

Web/push_notifications.py

@@ -142,7 +142,7 @@ def save_push_subscription(username, subscription_obj):
         # Create unique hash of subscription using plaintext data to avoid duplicates
         sub_hash = hashlib.shake_256(
             f"{username}:{endpoint}".encode('utf-8')
-        ).hexdigest()
+        ).hexdigest(32)
 
         # Check if subscription already exists by Hash
         existing = subs_col.find_one({
@@ -197,7 +197,7 @@ def remove_push_subscription(username, endpoint):
 
         sub_hash = hashlib.shake_256(
             f"{username}:{endpoint}".encode('utf-8')
-        ).hexdigest()
+        ).hexdigest(32)
 
         result = subs_col.update_one(
             {'SubscriptionHash': sub_hash},