Merge pull request #776 from OneSignal/fix/unity6-android-compatibility-gradle

Fix Unity 6 Android compatibility with gradle

Author: jkasten2

com.onesignal.unity.android/Editor/OneSignalConfig.androidlib/build.gradle

@@ -1,6 +1,8 @@
 apply plugin: 'com.android.library'
 
 android {
+    namespace 'com.onesignal.onesignalsdk'
+
     sourceSets {
         main {
             manifest.srcFile 'AndroidManifest.xml'
@@ -21,4 +23,4 @@ android {
     lintOptions {
         abortOnError false
     }
-}
+}