Make tests badge tool-agnostic

Author: hirasso

README.md

@@ -3,7 +3,7 @@
 <div class="shields">
 
 <!--[![npm version](https://img.shields.io/npm/v/@swup/fragment-plugin.svg)](https://www.npmjs.com/package/@swup/fragment-plugin) -->
-[![Test status](https://img.shields.io/github/actions/workflow/status/swup/fragment-plugin/unit-tests.yml?branch=master&label=Vitest)](https://github.com/swup/fragment-plugin/actions/workflows/unit-tests.yml)
+[![Test status](https://img.shields.io/github/actions/workflow/status/swup/fragment-plugin/unit-tests.yml?branch=master&label=unit%20tests)](https://github.com/swup/fragment-plugin/actions/workflows/unit-tests.yml)
 [![License](https://img.shields.io/github/license/swup/fragment-plugin.svg)](https://github.com/swup/fragment-plugin/blob/master/LICENSE)
 
 </div>