remove coveralls badge

Author: cenkalti

README.md

@@ -1,4 +1,4 @@
-# Exponential Backoff [![GoDoc][godoc image]][godoc] [![Coverage Status][coveralls image]][coveralls]
+# Exponential Backoff [![GoDoc][godoc image]][godoc]
 
 This is a Go port of the exponential backoff algorithm from [Google's HTTP Client Library for Java][google-http-java-client].
 
@@ -23,8 +23,6 @@ If you have specific needs, copy `Retry` function (from [retry.go][retry-src]) i
 
 [godoc]: https://pkg.go.dev/github.com/cenkalti/backoff/v5
 [godoc image]: https://godoc.org/github.com/cenkalti/backoff?status.png
-[coveralls]: https://coveralls.io/github/cenkalti/backoff?branch=v5
-[coveralls image]: https://coveralls.io/repos/github/cenkalti/backoff/badge.svg?branch=v5
 
 [google-http-java-client]: https://github.com/google/google-http-java-client/blob/da1aa993e90285ec18579f1553339b00e19b3ab5/google-http-client/src/main/java/com/google/api/client/util/ExponentialBackOff.java
 [exponential backoff wiki]: http://en.wikipedia.org/wiki/Exponential_backoff