feat: Update barcode scanner options

Update the code to use the `detectionSpeed` property instead of `allowDuplicates` to control the detection of multiple scans in a short time.

Author: itsarvinddev

README.md

@@ -100,7 +100,7 @@ Import `package:ai_barcode_scanner/ai_barcode_scanner.dart`, and use the widget
 
 If you don't provide a controller, you can't control functions like the torch(flash) or switching camera.
 
-If you don't set allowDuplicates to false, you can get multiple scans in a very short time, causing things like pop() to fire lots of times.
+If you don't set `detectionSpeed: DetectionSpeed.noDuplicates`, you can get multiple scans in a very short time.
 
 ```dart
 import 'package:ai_barcode_scanner/ai_barcode_scanner.dart';