feat: deserialize alternative format errors

[Justintime50]

Description

• Fixes error parsing
  • Allows for alternative format of errors field (previously we deserialized the errors field into a list of Error objects; however, sometimes the errors are simply a list of strings. This change make the errors field a list of Object allowing for either the new FieldError object or a list of strings. Users will need to check for the type of error returned and handle appropriately)
  • Removed the unused Error model
  • Added an explicit AddressVerificationFieldError model
  • The BetaPaymentRefund now uses a list of FieldError instead of Error for the errors field

Testing

• Add alternative error format test
• Add address verification error test

Pull Request Type

Please select the option(s) that are relevant to this PR.

• 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 not work as expected)
• Improvement (fixing a typo, updating readme, renaming a variable name, etc)