v2.3.0: Introduced Unified Trading Client

What's Changed

• feat(v2.3.0): introduced Unified Trading Client by @JJ-Cro in #92

The UnifiedAPIClient provides access to KuCoin's Unified API endpoints, which offer streamlined market data access across Spot, Futures, and Margin trading products. It doesn't serve a purpose of a UTA account(Unified trading account) - but it is a new generation of API endpoints generalised for all trading products.

Full Changelog: v2.2.0...v2.3.0