Add the mfa_serial profile property

[abrooksv]

Description

Add mfa_serial as defined here: https://docs.aws.amazon.com/cli/latest/topic/config-vars.html#using-aws-iam-roles

Motivation and Context

Adds standardized key to list of profile properties

Testing

mvn install

Screenshots (if appropriate)

Types of changes

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

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• 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

• I confirm that this pull request can be released under the Apache 2 license

[zoewangg]

🚢