doc: fixed broken link to codecov in readme

Signed-off-by: Frédéric BIDON <[email protected]>

README.md

@@ -1,4 +1,4 @@
-# Loads OAI specs [![Build Status](https://github.com/go-openapi/loads/actions/workflows/go-test.yml/badge.svg)](https://github.com/go-openapi/loads/actions?query=workflow%3A"go+test") [![codecov](https://codecov.io/gh/go-openapi/loads/branch/master/graph/badge.svg)](https://codecov.io/gh/go-openapi/lods)
+# Loads OAI specs [![Build Status](https://github.com/go-openapi/loads/actions/workflows/go-test.yml/badge.svg)](https://github.com/go-openapi/loads/actions?query=workflow%3A"go+test") [![codecov](https://codecov.io/gh/go-openapi/loads/branch/master/graph/badge.svg)](https://codecov.io/gh/go-openapi/loads)
 
 [![license](http://img.shields.io/badge/license-Apache%20v2-orange.svg)](https://raw.githubusercontent.com/go-openapi/loads/master/LICENSE) [![GoDoc](https://godoc.org/github.com/go-openapi/loads?status.svg)](http://godoc.org/github.com/go-openapi/loads)
 [![Go Report Card](https://goreportcard.com/badge/github.com/go-openapi/loads)](https://goreportcard.com/report/github.com/go-openapi/loads)