Update main checks workflow badge.

Author: davidlehn

README.md

@@ -2,7 +2,7 @@
 
 [![npm package](https://nodei.co/npm/node-forge.png?downloads=true&downloadRank=true&stars=true)](https://nodei.co/npm/node-forge/)
 
-[![Build status](https://img.shields.io/travis/digitalbazaar/forge.svg?branch=master)](https://travis-ci.org/digitalbazaar/forge)
+[![Build Status](https://github.com/digitalbazaar/forge/workflows/Main%20Checks/badge.svg)](https://github.com/digitalbazaar/forge/actions?query=workflow%3A%22Main+Checks%22)
 
 A native implementation of [TLS][] (and various other cryptographic tools) in
 [JavaScript][].