fix: correct CI badge in source-maps readme

packages/istanbul-lib-source-maps/README.md

@@ -1,11 +1,11 @@
 # istanbul-lib-source-maps
 
-[![Build Status](https://travis-ci.org/istanbuljs/istanbuljs.svg?branch=main)](https://travis-ci.org/istanbuljs/istanbuljs)
+[![Build Status](https://img.shields.io/github/actions/workflow/status/istanbuljs/istanbuljs/ci.yml?label=CI&logo=GitHub)](https://github.com/istanbuljs/istanbuljs/actions/workflows/ci.yml)
 
 Source map support for istanbuljs.
 
 ## Debugging
 
-_istanbul-lib-source-maps_ uses the [debug](https://www.npmjs.com/package/debug) module.
+`istanbul-lib-source-maps` uses the [debug](https://www.npmjs.com/package/debug) module.
 Run your application with the environment variable `DEBUG=istanbuljs`, to receive debug
 output.