doc: fixed typo in badge link

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

Author: fredbi

README.md

@@ -1,4 +1,4 @@
-# OpenAPI v2 object model [![Build Status](https://github.com/go-openapi/spec/actions/workflows/go-test.yaml/badge.svg)](https://github.com/go-openapi/strfmt/actions?query=workflow%3A"go+test") [![codecov](https://codecov.io/gh/go-openapi/spec/branch/master/graph/badge.svg)](https://codecov.io/gh/go-openapi/spec)
+# OpenAPI v2 object model [![Build Status](https://github.com/go-openapi/spec/actions/workflows/go-test.yml/badge.svg)](https://github.com/go-openapi/strfmt/actions?query=workflow%3A"go+test") [![codecov](https://codecov.io/gh/go-openapi/spec/branch/master/graph/badge.svg)](https://codecov.io/gh/go-openapi/spec)
 
 [![Slack Status](https://slackin.goswagger.io/badge.svg)](https://slackin.goswagger.io)
 [![license](http://img.shields.io/badge/license-Apache%20v2-orange.svg)](https://raw.githubusercontent.com/go-openapi/spec/master/LICENSE)