Update SDK to be compliant with spec v0.3.0

Update the SDK to be compliant with the v0.3.0 spec.

## Providers
 - [#129](https://github.com/open-feature/spec/pull/129) - Remove context transformation
 
## Hooks
 - [#125](https://github.com/open-feature/spec/pull/125) - Verify context merging order for before hooks

**Full Changelog**: https://github.com/open-feature/spec/compare/v0.2.0...v0.3.0