feat: Add ability to fetch SDGs data from BPS API

[ryanaidilp]

Description

I propose enhancing the FLUTTER STADATA SDK with a new feature that allows users to fetch SDGs (Sustainable Development Goals) data from the BPS (Badan Pusat Statistik) API. This enhancement will empower developers using the SDK to access and incorporate SDGs data into their Flutter applications seamlessly.

Requirements

• Implement a new function/method in the SDK that can retrieve SDGs data from the BPS API.

• Develop comprehensive unit tests for the newly added function/method to ensure its accuracy and reliability.

• Maintain a test coverage of no less than 90% for the newly introduced feature.

• Update the SDK's documentation to include instructions on how to use the new feature, complete with illustrative examples.

Additional Context

The BPS API provides valuable SDGs data, and the inclusion of this feature in the SDK will facilitate developers in integrating this data into their Flutter applications more efficiently. The documentation for the BPS API's SDGs endpoint can be found here.

To encourage contributions from the open-source community, I have labeled this feature request with "hacktoberfest," "feature," and "help wanted." Your assistance in implementing this feature would be highly appreciated!