chore(custom-resources): update python runtime for custom resources

[GavinZZ]

Issue # (if applicable)

Closes https://github.com/aws/aws-cdk/issues/31245

Reason for this change

Support latest python runtime that's available everywhere

Description of changes

Update custom resource handler runtime to python 3.11

Description of how you validated changes

All existing tests should pass

Checklist

• [ ] My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license