Update Gradle Plugin

• Updates the onesignal-gradle-plugin used in the demo project

Author: Nightsd01

examples/RNOneSignal/android/app/build.gradle

@@ -1,5 +1,10 @@
-plugins {
-    id 'com.onesignal.androidsdk.onesignal-gradle-plugin' version '0.8.1'
+buildscript {
+    repositories {
+        maven { url 'https://plugins.gradle.org/m2/'}
+    }
+    dependencies {
+        classpath 'gradle.plugin.com.onesignal:onesignal-gradle-plugin:[0.10.0, 0.99.99]'
+    }
 }
 apply plugin: 'com.onesignal.androidsdk.onesignal-gradle-plugin'