Added Python version on README

README.md

 # Car Rental Flask API
 
 This is a small Flask application exposing CRUD endpoints for Car Reservations using SQLAlchemy and MySQL.
-
-Environment variables (or set a DATABASE_URL):
-
-- MYSQL_USER (default: root)
-- MYSQL_PASSWORD (default: root)
-- MYSQL_HOST (default: localhost)
-- MYSQL_PORT (default: 3306)
-- MYSQL_DB (default: car_rental)
-- DATABASE_URL (optional; overrides the pieces above)
+This web api works with python 3.13.3
 
 Install dependencies: