maint: Fix build status badge (#3755)

Author: mathbunnyru

README.md

@@ -18,7 +18,7 @@
 
 # mamba
 
-[![Build Status](https://github.com/mamba-org/mamba/workflows/CI/badge.svg)](https://github.com/mamba-org/mamba/actions)
+[![Build Status](https://github.com/mamba-org/mamba/actions/workflows/tests.yml/badge.svg)](https://github.com/mamba-org/mamba/actions/workflows/tests.yml?query=branch%3Amain)
 [![Join the Gitter Chat](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/mamba-org/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![docs](https://readthedocs.org/projects/mamba/badge/?version=latest&style=flat)](https://mamba.readthedocs.io/en/latest)
 [![Gurubase](https://img.shields.io/badge/Gurubase-Ask%20mamba%20Guru-006BFF)](https://gurubase.io/g/mamba)