Remove AD ID permission added by firebase

We're not actually using this for anything, and Firebase is confirmed to work without it.

app/src/main/AndroidManifest.xml

@@ -1,11 +1,16 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     package="com.willowtree.vocable">
 
     <uses-permission android:name="android.permission.CAMERA" />
 
     <uses-feature android:name="android.hardware.camera.ar" />
 
+    <uses-permission
+        android:name="com.google.android.gms.permission.AD_ID"
+        tools:node="remove" />
+
     <application
         android:name=".VocableApp"
         android:allowBackup="false"