Use correct badge, remove travis (#47)

Author: lucacome

README.md

@@ -1,5 +1,5 @@
 # NGINX Plus - NS1 Global Server Load Balancing
-[![Build Status](https://travis-ci.org/nginxinc/nginx-ns1-gslb.svg?branch=master)](https://travis-ci.org/nginxinc/nginx-ns1-gslb)
+[![Continuous Integration](https://github.com/nginxinc/nginx-ns1-gslb/actions/workflows/ci.yml/badge.svg)](https://github.com/nginxinc/nginx-ns1-gslb/actions/workflows/ci.yml)
 [![FOSSA Status](https://app.fossa.com/api/projects/custom%2B5618%2Fgithub.com%2Fnginxinc%2Fnginx-ns1-gslb.svg?type=shield)](https://app.fossa.com/projects/custom%2B5618%2Fgithub.com%2Fnginxinc%2Fnginx-ns1-gslb?ref=badge_shield)
 [![Go Report Card](https://goreportcard.com/badge/github.com/nginxinc/nginx-ns1-gslb)](https://goreportcard.com/report/github.com/nginxinc/nginx-ns1-gslb)