docs: update bullet on testing

README.md

@@ -6,9 +6,8 @@
 This project is an exercise in developing good clean architecture and CI/CD practices. It includes (or will include):
 
 * Infrastructure as Code with [Pulumi](https://www.pulumi.com/), including automatic provisioning of preview environments for each PR.
-* CI including linting, unit and integration tests.
+* CI including linting, unit, integration and mutation tests.
   * [ ] TODO: Eventually end to end tests with Playwright.
-  * [ ] TODO: Add mutation tests for API.
 * A clean architecture, including dependency inversion enforced through linting rules with [eslint-plugin-boundaries](https://github.com/javierbrea/eslint-plugin-boundaries).
 * Continuous delivery practices, including automatic deployments to staging and production environments.
 * [ ] TODO: Automatic dependency updates (including automerging for minor version changes) with Renovate.