chore: bump boto3, botocore min versions to 1.16.8, 1.19.8 resp

[Brooke-white]

Description

Bumps minimum version for boto3 to 1.16.8
Bumps minimum version for botoxore to 1.19.8

Motivation and Context

Testing

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• Local run of python3 setup.py succeeds
• My code follows the code style of this project
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed
• A short description of the change has been added to the CHANGELOG

License

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