1. Add spot cross margin API support
2. Add spot order operations using cross margin account
3. Withdrawal supports cancelling
4. Futures positions supports updating cross margin leverage
5. Add interest in spot margin account response

1. Add GateApiException. Refer to API documents for details
2. Add orders_limit in futures Contract model; size in FuturesOrder is required

4.15.2 release add support for all APIs since 4.14.0, along with some new features:

1. All API call method and model fields add type hints in docstring, so that you can get code completion in your favourite IDE
2. The authentication process has been rewritten. For details about how to use it. Refer to API documentation