chore: Only use master test runs for status badge (#3475)

Author: iCiaran

README.md

@@ -2,7 +2,7 @@
 
 [![go-github release (latest SemVer)](https://img.shields.io/github/v/release/google/go-github?sort=semver)](https://github.com/google/go-github/releases)
 [![Go Reference](https://img.shields.io/static/v1?label=godoc&message=reference&color=blue)](https://pkg.go.dev/github.com/google/go-github/v69/github)
-[![Test Status](https://github.com/google/go-github/workflows/tests/badge.svg)](https://github.com/google/go-github/actions?query=workflow%3Atests)
+[![Test Status](https://github.com/google/go-github/actions/workflows/tests.yml/badge.svg?branch=master)](https://github.com/google/go-github/actions/workflows/tests.yml)
 [![Test Coverage](https://codecov.io/gh/google/go-github/branch/master/graph/badge.svg)](https://codecov.io/gh/google/go-github)
 [![Discuss at [email protected]](https://img.shields.io/badge/discuss-go--github%40googlegroups.com-blue.svg)](https://groups.google.com/group/go-github)
 [![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/796/badge)](https://bestpractices.coreinfrastructure.org/projects/796)