Change build status badge (#269)

Co-authored-by: Damien Neil <neild@users.noreply.github.com>

README.md

@@ -1,7 +1,7 @@
 # Package for equality of Go values
 
 [![GoDev](https://img.shields.io/static/v1?label=godev&message=reference&color=00add8)][godev]
-[![Build Status](https://travis-ci.org/google/go-cmp.svg?branch=master)][travis]
+[![Build Status](https://github.com/google/go-cmp/actions/workflows/test.yml/badge.svg?branch=master)][actions]
 
 This package is intended to be a more powerful and safer alternative to
 `reflect.DeepEqual` for comparing whether two values are semantically equal.
@@ -29,7 +29,7 @@ See the [documentation][godev] for more information.
 This is not an official Google product.
 
 [godev]: https://pkg.go.dev/github.com/google/go-cmp/cmp
-[travis]: https://travis-ci.org/google/go-cmp
+[actions]: https://github.com/google/go-cmp/actions
 
 ## Install