message: Add macOS badge
diff: <img src="https://github.com/bark-simulator/bark/raw/master/docs/source/bark_logo.jpg" alt="BARK" />
  </p>
  -![CI Build](https://github.com/bark-simulator/bark/workflows/CI/badge.svg)
  +![Ubtuntu-CI Build](https://github.com/bark-simulator/bark/workflows/CI/badge.svg)
  +![macOS-CI Build](https://github.com/bark-simulator/bark/workflows/macOS-CI/badge.svg)
  ![NIGHTLY Build](https://github.com/bark-simulator/bark/workflows/NIGHTLY/badge.svg)
  ![NIGHTLY LTL Build](https://github.com/bark-simulator/bark/workflows/NIGHTLY_LTL/badge.svg)
  