feat: set python 3.8 as default hosted skill python runtime version

[skrotha]

Description

This Change allows the usage of python3.8 as default python run time for Alexa Hosted Skills.

Motivation and Context

Testing

This change is being released after testing in beta and gamma testing.

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed
• My commit message follows Conventional Commit Guideline

License

• By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.