[seL4] Release 2.0.0 of Microkit

Hello everyone, There is a new release of Microkit, version 2.0.0. This release contains various bug fixes, quality-of-life changes, features, and new board support. This is a major version bump due to a breaking change. Below the release notes, there is a section on how to upgrade from Microkit 1.4.1. You can download the pre-built SDK from GitHub: https://github.com/seL4/microkit/releases/tag/2.0.0 Ivan