message: chore: add codecov badge
diff: # ts-graphql-plugin
  -[![github actions](https://github.com/Quramy/ts-graphql-plugin/workflows/build/badge.svg)](https://github.com/Quramy/ts-graphql-plugin/actions) [![npm version](https://badge.fury.io/js/ts-graphql-plugin.svg)](https://badge.fury.io/js/ts-graphql-plugin) ![deps](https://david-dm.org/quramy/ts-graphql-plugin.svg) [![Greenkeeper badge](https://badges.greenkeeper.io/Quramy/ts-graphql-plugin.svg)](https://greenkeeper.io/) [![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/Quramy/ts-graphql-plugin/master/LICENSE.txt)
  +[![github actions](https://github.com/Quramy/ts-graphql-plugin/workflows/build/badge.svg)](https://github.com/Quramy/ts-graphql-plugin/actions)
  +[![codecov](https://codecov.io/gh/Quramy/ts-graphql-plugin/branch/master/graph/badge.svg)](https://codecov.io/gh/Quramy/ts-graphql-plugin)
  +[![npm version](https://badge.fury.io/js/ts-graphql-plugin.svg)](https://badge.fury.io/js/ts-graphql-plugin)
  +![deps](https://david-dm.org/quramy/ts-graphql-plugin.svg) [![Greenkeeper badge](https://badges.greenkeeper.io/Quramy/ts-graphql-plugin.svg)](https://greenkeeper.io/)
  +[![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/Quramy/ts-graphql-plugin/master/LICENSE.txt)
  Provides functions to help TypeScript GraphQL client development including auto completion, query validation, type generation and so on.
  