README: fix badge

Author: matthewdouglas

README.md

@@ -3,7 +3,7 @@
 <p align="center">
     <a href="https://github.com/bitsandbytes-foundation/bitsandbytes/main/LICENSE"><img alt="License" src="https://img.shields.io/github/license/bitsandbytes-foundation/bitsandbytes.svg?color=blue"></a>
     <a href="https://pepy.tech/project/bitsandbytes"><img alt="Downloads" src="https://static.pepy.tech/badge/bitsandbytes/month"></a>
-    <a href="https://github.com/bitsandbytes-foundation/bitsandbytes/actions/workflows/tests-nightly.yml"><img alt="Nightly Unit Tests" src="https://img.shields.io/github/actions/workflow/status/bitsandbytes-foundation/bitsandbytes/tests.yml?logo=github&label=Nightly%20Tests"></a>
+    <a href="https://github.com/bitsandbytes-foundation/bitsandbytes/actions/workflows/tests-nightly.yml"><img alt="Nightly Unit Tests" src="https://img.shields.io/github/actions/workflow/status/bitsandbytes-foundation/bitsandbytes/tests-nightly.yml?logo=github&label=Nightly%20Tests"></a>
     <a href="https://github.com/bitsandbytes-foundation/bitsandbytes/releases"><img alt="GitHub Release" src="https://img.shields.io/github/v/release/bitsandbytes-foundation/bitsandbytes"></a>
     <a href="https://pypi.org/project/bitsandbytes/"><img alt="PyPI - Python Version" src="https://img.shields.io/pypi/pyversions/bitsandbytes"></a>
 </p>