update README SDK build status badge (#824)

Updates the README doc's SDK build status badge.

Author: jasdel

README.md

@@ -1,6 +1,6 @@
 # AWS SDK for Go v2
 
-![Build Status](https://codebuild.us-west-2.amazonaws.com/badges?uuid=eyJlbmNyeXB0ZWREYXRhIjoib1lGQ3N6RFJsalI5a3BPcXB3Rytaak9kYVh1ZW1lZExPNjgzaU9Udng3VE5OL1I3czIwcVhkMUlUeG91ajBVaWRYcVVJSEVQcmZwTWVyT1p5MGszbnA4PSIsIml2UGFyYW1ldGVyU3BlYyI6IkhrZ1VMN20zRmtYY1BrR0wiLCJtYXRlcmlhbFNldFNlcmlhbCI6MX0%3D&branch=master) [![API Reference](https://img.shields.io/badge/api-reference-blue.svg)](https://pkg.go.dev/mod/github.com/aws/aws-sdk-go-v2) [![Apache V2 License](https://img.shields.io/badge/license-Apache%20V2-blue.svg)](https://github.com/aws/aws-sdk-go/blob/master/LICENSE.txt)
+![Build Status](https://travis-ci.org/aws/aws-sdk-go-v2.svg?branch=master) [![API Reference](https://img.shields.io/badge/api-reference-blue.svg)](https://pkg.go.dev/mod/github.com/aws/aws-sdk-go-v2) [![Apache V2 License](https://img.shields.io/badge/license-Apache%20V2-blue.svg)](https://github.com/aws/aws-sdk-go/blob/master/LICENSE.txt)
 
 
 `aws-sdk-go-v2` is the **Developer Preview** (aka **beta**) for the v2 AWS SDK for the Go programming language. This Developer Preview is provided to receive feedback from the language community on SDK changes prior to the final release. As such users should expect the SDK to release minor version releases that break backwards compatability. The release notes for the breaking change will include information about the breaking change, and how you can migrate to the latest version.