[docs] fix Maintainability badge

Author: markets

README.md

@@ -2,7 +2,7 @@
 
 [![Gem](https://img.shields.io/gem/v/mini_i18n.svg?style=flat-square)](https://rubygems.org/gems/mini_i18n)
 [![Build Status](https://github.com/markets/mini_i18n/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/markets/mini_i18n/actions)
-[![Maintainability](https://api.codeclimate.com/v1/badges/9d82e7151f8a5594da0f/maintainability)](https://codeclimate.com/github/markets/mini_i18n/maintainability)
+[![Maintainability](https://qlty.sh/gh/markets/projects/mini_i18n/maintainability.svg)](https://qlty.sh/gh/markets/projects/mini_i18n)
 
 > Minimalistic i18n library for Ruby