docs: Fix build badge to point GH Actions CI (#1844)

Author: valfirst

README.md

@@ -2,7 +2,7 @@
 
 [![Maven Central](https://maven-badges.herokuapp.com/maven-central/io.appium/java-client/badge.svg)](https://maven-badges.herokuapp.com/maven-central/io.appium/java-client)
 [![Javadocs](https://www.javadoc.io/badge/io.appium/java-client.svg)](https://www.javadoc.io/doc/io.appium/java-client)
-[![Build Status](https://travis-ci.org/appium/java-client.svg?branch=master)](https://travis-ci.org/appium/java-client)
+[![Appium Java Client CI](https://github.com/appium/java-client/actions/workflows/gradle.yml/badge.svg)](https://github.com/appium/java-client/actions/workflows/gradle.yml)
 
 This is the Java language bindings for writing Appium Tests that conform to [WebDriver Protocol](https://w3c.github.io/webdriver/)