remove builder from the zoom slider example

@@ -91,9 +91,7 @@ class _BarcodeScannerWithZoomState extends State<BarcodeScannerWithZoom>
     return Scaffold(
       appBar: AppBar(title: const Text('With zoom slider')),
       backgroundColor: Colors.black,
-      body: Builder(
-        builder: (context) {
-          return Stack(
+      body: Stack(
         children: [
           MobileScanner(
             controller: controller,
@@ -142,8 +140,6 @@ class _BarcodeScannerWithZoomState extends State<BarcodeScannerWithZoom>
             ),
           ),
         ],
-          );
-        },
       ),
     );
   }