Update build status label to show Github Actions

This replaces Travis-CI badge which is no longer in use.

Signed-off-by: Brian Wagner <briwagner@outlook.com>

README.md

@@ -1,6 +1,6 @@
 ## OpenFaaS ® - Serverless Functions Made Simple
 
-[![Build Status](https://travis-ci.com/openfaas/faas.svg?branch=master)](https://travis-ci.com/openfaas/faas)
+[![Build Status](https://github.com/openfaas/faas/actions/workflows/build.yml/badge.svg)](https://travis-ci.com/openfaas/faas)
 [![go.dev reference](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/github.com/openfaas/faas)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![OpenFaaS](https://img.shields.io/badge/openfaas-serverless-blue.svg)](https://www.openfaas.com)
@@ -47,7 +47,7 @@ Official templates exist for many popular languages and are easily extensible wi
 
     ```js
    "use strict"
-   
+
     module.exports = async (event, context) => {
         return context
             .status(200)
@@ -57,7 +57,7 @@ Official templates exist for many popular languages and are easily extensible wi
                 👋 Hello World 🌍
             </h1>`);
     }
- 
+
     ```
     *handler.js*