Ntropy-sdk

- Allow subnormal float values in pydantic fields
- Fix bug with inplace=False for dataframe enrichment
- Added tests for models module
- Updated scikit-compatible model to use SDK Model class
- Include original Transaction object in EnrichedTransaction
- Support iterables in `add_transactions` and `add_transactions_async`
- Ensure that `to_dict()` method always returns values even if None, but only returned fields that the API returns
- Added support for income checking API (IncomeReport, IncomeGroup)

- Add repeating label to recurrence

- Renamed `predicted_mcc` to `mcc` for simplicity.
- Increased mcc range to 700-9999

- Fixed a bug with deprecated `model` parameter for custom models

- Added TCP keep-alive to Ntropy API requests
- Migrated SDK classes to Pydantic (support for Decimal and str in numerical fields)
- Added new predicted_mcc field in EnrichedTransaction

- Update `get_account_holder` method to return an AccountHolder object instead of dictionaries
- Added docstrings to all public SDK methods. Consult the reference at https://developers.ntropy.com/sdk
- Added `retries` attribute to SDK object, which determines the number of retries per request before failling
- Added `retry_on_unhandled_exception` to SDK object, which controls whether the SDK should retry requests that return an error code in the range 500-511
- Removed `list_models` method. Added base custom model API to SDK that closer resembles the REST API structure. Added three new methods to SDK `train_custom_model`, `get_custom_model` and `get_all_custom_models`. Added new classes to represent custom model structures `LabeledTransaction` and `Model`.