chore(synthetics): selenium 6.0 runtime (#34663)

### Issue # (if applicable)
None

### Reason for this change
https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CloudWatch_Synthetics_Library_python_selenium.html

### Description of changes
- Add selenium 6.0 runtime

### Describe any new or updated permissions being added
None

### Description of how you validated changes
Unit + Integ

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

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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*

Author: phuhung273