Update code coverage badge in README.md to reflect new percentage

Author: btungut

README.md

@@ -1,7 +1,7 @@
 # `kubeconfig-merge`: Painless and faultless way to merge kubeconfig files
 ---
 ![release](https://img.shields.io/github/v/release/btungut/kubeconfig-merge)
-![Code Coverage](https://img.shields.io/badge/Code%20Coverage-51%25-yellow?style=flat)
+![Code Coverage](https://img.shields.io/badge/Code%20Coverage-56%25-yellow?style=flat)
 ![build](https://img.shields.io/github/actions/workflow/status/btungut/kubeconfig-merge/ci.yml?branch=master)
 ![go](https://img.shields.io/github/go-mod/go-version/btungut/kubeconfig-merge)