Add CI badge in the readme

Author: radare

README.md

@@ -1,5 +1,7 @@
 # Minimalistic ZIP Implementation (mzip)
 
+[![CI](https://github.com/trufae/mzip/actions/workflows/ci.yml/badge.svg)](https://github.com/trufae/mzip/actions/workflows/ci.yml)
+
 This is a minimalistic implementation of the ZIP file format, designed to be small, portable, and dependency-free.
 
 **NOTE** This code has been initially written by Claude Code