docs: update badge

Author: setchy

README.md

@@ -56,6 +56,6 @@ For more information, see [LICENSE](LICENSE).
 [license]: LICENSE
 [license-badge]: https://img.shields.io/github/license/gitify-app/gitify?logo=github
 [github-release-badge]: https://img.shields.io/github/v/release/gitify-app/gitify?logo=github
-[homebrew-cask-badge]: https://img.shields.io/homebrew/cask/v/gitify?logo=homebrew
+[homebrew-cask-badge]: https://img.shields.io/homebrew/cask/v/gitify?logo=homebrew&logoColor=white
 [renovate]: https://renovatebot.com/
 [renovate-badge]: https://img.shields.io/badge/renovate-enabled-brightgreen.svg?logo=renovate&logoColor=white