Update CI badge in README.md

Author: ocramz

README.md

@@ -2,7 +2,8 @@
 
 Numerical computation in native Haskell
 
-[![Hackage](https://img.shields.io/hackage/v/sparse-linear-algebra.svg)](https://hackage.haskell.org/package/sparse-linear-algebra)  [![Build Status](https://travis-ci.org/ocramz/sparse-linear-algebra.png)](https://travis-ci.org/ocramz/sparse-linear-algebra)
+[![CI](https://github.com/ocramz/sparse-linear-algebra/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/ocramz/sparse-linear-algebra/actions/workflows/ci.yml)
+[![Hackage](https://img.shields.io/hackage/v/sparse-linear-algebra.svg)](https://hackage.haskell.org/package/sparse-linear-algebra)  
 [![sparse-linear-algebra](http://stackage.org/package/sparse-linear-algebra/badge/lts)](http://stackage.org/lts/package/sparse-linear-algebra)
 [![sparse-linear-algebra](http://stackage.org/package/sparse-linear-algebra/badge/nightly)](http://stackage.org/nightly/package/sparse-linear-algebra)
 
@@ -245,4 +246,4 @@ Inspired by
 
 [6] M. M. T. Chakravarty, et al., Accelerating Haskell array codes with multicore GPUs - DAMP'11
 
-[7] [`accelerate`](http://hackage.haskell.org/package/accelerate)
+[7] [`accelerate`](http://hackage.haskell.org/package/accelerate)