reduce default time delta and allowed to be modified with variable

.env.example

@@ -8,3 +8,4 @@ QL_0=
 IBSID=
 
 APP_DEBUG=true
+TIME_DIFF_LIMIT=1

api.py

@@ -9,6 +9,7 @@ import json
 from datetime import datetime, timedelta
 
 load_dotenv()  # This will load environment variables from a .env file if it exists
+TIME_DIFF_LIMIT = int(os.getenv('TIME_DIFF_LIMIT', 2))  # Default to 2mins if not set
 
 app = Flask(__name__)
 
@@ -36,7 +37,7 @@ def verify_transaction(benef_name, abs_amount, request_time, tx_data_list):
             
             if (tx_benef_name == benef_name.strip().lower() and
                 compare_amounts(tx_data['absAmount'], abs_amount) and
-                time_diff <= timedelta(minutes=30)):
+                time_diff <= timedelta(minutes=TIME_DIFF_LIMIT)):
                 return True
         except ValueError as e:
             app.logger.error(f"Error processing transaction: {str(e)}")