Configure Android namespace to fix missing namespace issue on Gradle >= 8.x

Author: h3x4d3c1m4l

android/build.gradle

@@ -25,6 +25,8 @@ rootProject.allprojects {
 apply plugin: 'com.android.library'
 
 android {
+    namespace 'com.pdftron.pdftronflutter'
+
     compileSdkVersion 33
 
     defaultConfig {

android/src/main/AndroidManifest.xml

@@ -1,5 +1,4 @@
-<manifest xmlns:android="http://schemas.android.com/apk/res/android"
-    package="com.pdftron.pdftronflutter">
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
 
     <application>