docs: remove maintainability badge (#19)

Author: usamabintariq

README.md

@@ -3,7 +3,6 @@
 [![Version][nuget-version]][nuget-url]
 [![Build & Tests][test-badge]][test-url]
 [![Test Coverage][coverage-badge]][coverage-url]
-[![Maintainability][maintainability-badge]][maintainability-url]
 [![Licence][license-badge]][license-url]
 
 ## Introduction
@@ -33,7 +32,5 @@ This project contains core logic and the utilities for the APIMatic's C# SDK
 [test-url]: https://github.com/apimatic/core-lib-csharp/actions/workflows/test.yml
 [coverage-badge]: https://api.codeclimate.com/v1/badges/d613a5f73f605369e745/test_coverage
 [coverage-url]: https://codeclimate.com/github/apimatic/core-lib-csharp/test_coverage
-[maintainability-badge]: https://api.codeclimate.com/v1/badges/d613a5f73f605369e745/maintainability
-[maintainability-url]: https://codeclimate.com/github/apimatic/core-lib-csharp/maintainability
 [license-badge]: https://img.shields.io/badge/licence-APIMATIC-blue
 [license-url]: LICENSE