docs: add code coverage badge

README.md

@@ -5,6 +5,7 @@
 [![GitHub go.mod Go version](https://badges.chse.dev/github/go-mod/go-version/Tochemey/goakt)](https://go.dev/doc/install)
 ![GitHub Release](https://img.shields.io/github/v/release/Tochemey/goakt)
 [![Go Report Card](https://goreportcard.com/badge/github.com/tochemey/goakt)](https://goreportcard.com/report/github.com/tochemey/goakt)
+[![codecov](https://codecov.io/gh/Tochemey/goakt/graph/badge.svg?token=J0p9MzwSRH)](https://codecov.io/gh/Tochemey/goakt)
 
 Distributed [Go](https://go.dev/) actor framework to build reactive and distributed system in golang using
 _**protocol buffers as actor messages**_.