README: Update image shields badge

Update broken badge as mentioned in badges/shields#8671

Author: kbdharun

README.md

@@ -1,6 +1,6 @@
 # tldr c client
 
-[![Build Status](https://img.shields.io/github/workflow/status/tldr-pages/tldr-c-client/Tests.svg?style=flat-square)](https://github.com/tldr-pages/tldr-c-client/actions)
+[![Build Status](https://img.shields.io/github/actions/workflow/status/tldr-pages/tldr-c-client/.github/workflows/tests.yml?branch=main)](https://github.com/tldr-pages/tldr-c-client/actions)
 
 A command line client for tldr, written in plain ISO C90.