Your company offers a web portal to match developers to clients who need their help. As a Solutions Architect, you've designed the architecture of the website to follow some serverless pattern on the API side, with API Gateway and AWS Lambda. The backend is leveraging an RDS PostgreSQL database. Currently, you are using a classic username and password combination to connect the Lambda function to the RDS database. You would like to implement greater security at the authentication level, leveraging short lived credentials. What do you recommend?