chore: bump lambda runtime to python 3.13 (EOL 3.9) #606

[DocEight]

With Python 3.9 reaching EOL in October of this year (2025), I’ve raised this pull request to bump Lambda’s runtime to 3.13

※ According to the docs Boto3 is compatible with Python 3.9 and up: https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html#install-or-update-python I’ve also raised the following PR to bump the runtime to Python 3.10, in case you feel that this would be a safer move :) https://github.com/pahud/cdk-remote-stack/pull/607
 If you choose to merge this PR, please feel free to close the other!