Update travis link to travis-ci.com & main

Author: jkasten2

README.md

@@ -3,7 +3,7 @@
 </p>
 
 ### OneSignal Android Push Notification Plugin
-[![Maven Central](https://maven-badges.herokuapp.com/maven-central/com.onesignal/OneSignal/badge.svg)](https://maven-badges.herokuapp.com/maven-central/com.onesignal/OneSignal) [![Build Status](https://travis-ci.org/OneSignal/OneSignal-Android-SDK.svg?branch=master)](https://travis-ci.org/OneSignal/OneSignal-Android-SDK)
+[![Maven Central](https://maven-badges.herokuapp.com/maven-central/com.onesignal/OneSignal/badge.svg)](https://maven-badges.herokuapp.com/maven-central/com.onesignal/OneSignal) [![Build Status](https://app.travis-ci.com/OneSignal/OneSignal-Android-SDK.svg?branch=main)](https://app.travis-ci.com/OneSignal/OneSignal-Android-SDK)
 
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