android: update Android Gradle Plugin as recommended by Android Studio

Updates #cleanup

android/build.gradle

@@ -4,7 +4,7 @@ buildscript {
 		jcenter()
 	}
 	dependencies {
-		classpath 'com.android.tools.build:gradle:7.3.0'
+		classpath 'com.android.tools.build:gradle:7.4.2'
 	}
 }
 
@@ -43,6 +43,7 @@ android {
 			// The play flavor contains all features and is for the Play Store.
 		}
 	}
+    namespace 'com.tailscale.ipn'
 }
 
 dependencies {

android/src/main/AndroidManifest.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
-	package="com.tailscale.ipn">
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
 	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 	<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
 	<uses-permission android:name="android.permission.INTERNET" />