Revert "Added scanInvert method in flutter_qr_web"

This reverts commit 36577c007d.

lib/src/web/flutter_qr_web.dart

@@ -309,12 +309,6 @@ class QRViewControllerWeb implements QRViewController {
     // TODO: flash is simply not supported by JavaScipt
     return;
   }
-
-  @override
-  Future<void> scanInvert(bool isScanInvert) {
-    // TODO: implement scanInvert
-    throw UnimplementedError();
-  }
 }
 
 Widget createWebQrView({onPlatformViewCreated, CameraFacing? cameraFacing}) =>