docs: replaces Travis CI badge with GitHub Actions badges

Author: mattxwang

README.md

@@ -1,6 +1,6 @@
 # Kubernetes Autoscaler
 
-[![Build Status](https://travis-ci.org/kubernetes/autoscaler.svg?branch=master)](https://travis-ci.org/kubernetes/autoscaler) [![GoDoc Widget]][GoDoc]
+[![Release Charts](https://github.com/kubernetes/autoscaler/actions/workflows/release.yaml/badge.svg)](https://github.com/kubernetes/autoscaler/actions/workflows/release.yaml) [![Tests](https://github.com/kubernetes/autoscaler/actions/workflows/ci.yaml/badge.svg)](https://github.com/kubernetes/autoscaler/actions/workflows/ci.yaml) [![GoDoc Widget]][GoDoc]
 
 This repository contains autoscaling-related components for Kubernetes.