Update README badge link to point to the main branch for unit tests

Author: ceelsoin

README.md

@@ -1,7 +1,7 @@
 
 # go-qs
 
-[![Go Reference](https://pkg.go.dev/badge/github.com/globocom/go-qs.svg)](https://pkg.go.dev/github.com/globocom/go-qs) [![Unit tests](https://github.com/globocom/go-qs/actions/workflows/tests.yaml/badge.svg)](https://github.com/globocom/go-qs/actions/workflows/tests.yaml)
+[![Go Reference](https://pkg.go.dev/badge/github.com/globocom/go-qs.svg)](https://pkg.go.dev/github.com/globocom/go-qs) [![Unit tests](https://github.com/globocom/go-qs/actions/workflows/tests.yaml/badge.svg?branch=main)](https://github.com/globocom/go-qs/actions/workflows/tests.yaml)
 
 > Parse and decode URL query strings into nested Go data structures. Compatible with [javascript qs](npmjs.com/package/qs).