Update status badge in Readme [skip ci]

Author: aminya

Diff for: README.md

@@ -1,4 +1,6 @@
-# Git Node module [![Build Status](https://travis-ci.org/atom/git-utils.svg?branch=master)](https://travis-ci.org/atom/git-utils) [![Build status](https://ci.appveyor.com/api/projects/status/myrqbxes1mv8b472?svg=true)](https://ci.appveyor.com/project/Atom/git-utils)
+# Git Node module
+
+![ci](https://github.com/atom/git-utils/workflows/ci/badge.svg)
 
 
 Helpers for working with Git repositories built natively on top of