feat: Implement logic to prevent deletion of system tasks and rewards; update APIs and tests accordingly

backend/api/auth_api.py

@@ -3,7 +3,7 @@ import secrets, jwt
 from datetime import datetime, timedelta, timezone
 from models.user import User
 from flask import Blueprint, request, jsonify, current_app
-from backend.utils.email_instance import email_sender
+from utils.email_instance import email_sender
 from tinydb import Query
 import os