Fix github status badge

README.md

@@ -9,7 +9,7 @@
 <div align="center">
   <a href="https://pypi.python.org/pypi/labelme"><img src="https://img.shields.io/pypi/v/labelme.svg"></a>
   <a href="https://pypi.org/project/labelme"><img src="https://img.shields.io/pypi/pyversions/labelme.svg"></a>
-  <a href="https://github.com/wkentaro/labelme/actions"><img src="https://github.com/wkentaro/labelme/workflows/ci/badge.svg?branch=main&event=push"></a>
+  <a href="https://github.com/wkentaro/labelme/actions"><img src="https://github.com/wkentaro/labelme/actions/workflows/ci.yml/badge.svg?branch=main&event=push"></a>
 </div>
 
 <div align="center">