Updates
* Added `bank_account_type` SEP-9 field (679)
Dependencies
* Updated [cryptography](https://pypi.org/project/cryptography/) to `^39` (#684)
* **NOTE**: This is a major version change for the package. No changes were required in Polaris, but make sure to check the [changelog](https://cryptography.io/en/latest/changelog/) if you use this package in your application.
Bug Fixes
* Added support for SEP-31 transactions to the default registered fee function, `polaris.integrations.fees.calculate_fee()` (680)
* Calculate fees for SEP-6 withdrawal transactions in `execute_outgoing_transactions` if the fee has not yet been set (680)