move away from deprecated package attribute

app/build.gradle.kts

@@ -35,6 +35,8 @@ android {
     compileSdk = 33
     buildToolsVersion = "33.0.0"
 
+    namespace = "app.grapheneos.pdfviewer"
+
     defaultConfig {
         applicationId = "app.grapheneos.pdfviewer"
         minSdk = 26

app/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="app.grapheneos.pdfviewer"
         android:targetSandboxVersion="2">
     <original-package android:name="org.grapheneos.pdfviewer" />