(RDS): Rotation applications are very old and insecure

### What is the problem?

I deployed a MySQL RDS instance in isolated subnets and added a lambda to rotate the database credentials using the `addRotationMultiUser` method. The Lambda function is provision correctly, but fails when it call the `set_secret` method. Connecting to the database fails with the following error:

`[ERROR] ModuleNotFoundError: No module named 'asn1crypto' Traceback (most recent call last): File "/var/task/lambda_function.py", line 78, in lambda_handler `

The dependency could be missing or the issue could be caused by a version update. Lock the version using a requirements.txt file when installing the dependencies.
`pip install -r requirements.txt`

### Reproduction Steps

[rds-stack.txt](https://github.com/aws/aws-cdk/files/7803428/rds-stack.txt)

### What did you expect to happen?

Create the "Secrets Manager RDS MySQL Handler" Lambda and rotate the database credentials successfully without throwing errors.

### What actually happened?

[ERROR] ModuleNotFoundError: No module named 'asn1crypto' Traceback (most recent call last): File "/var/task/lambda_function.py", line 78, in lambda_handler

### CDK CLI Version

1.137.0

### Framework Version

_No response_

### Node.js Version

14.15.5

### OS

macOS Big Sur Version 11.6.2

### Language

Typescript

### Language Version

3.9.7

### Other information

_No response_

Start with the linked rds-stack.txt reproduction and the generated lambda_function.py, focusing on the set_secret path used by addRotationMultiUser. Check how the rotation Lambda packages its dependencies and whether requirements.txt is involved; done means the Secrets Manager RDS MySQL Handler can rotate credentials without the asn1crypto error.

Written by the indexing model from the issue text.