update SDL3 from 3.2.20 to 3.4.2

libs/SDL3/test/android/cmake/AndroidManifest.xml.cmake

@@ -44,6 +44,7 @@
         android:label="@string/label"
         android:supportsRtl="true"
         android:theme="@style/AppTheme"
+        android:enableOnBackInvokedCallback="false"
         android:hardwareAccelerated="true">
         <activity
             android:name="@ANDROID_MANIFEST_PACKAGE@.SDLTestActivity"

libs/SDL3/test/android/cmake/SDLEntryTestActivity.java.cmake

@@ -8,7 +8,6 @@ import android.content.Intent;
 import android.os.Bundle;
 import android.util.Log;
 
-import org.libsdl.app.SDL;
 import org.libsdl.app.SDLActivity;
 
 import android.widget.Button;