[go_router_builder] Skip case sensitive test (#9444)

Part of  flutter/flutter#169809

Prepare for #9426, this skips a test that needs to migrated with the new version of `go_router`.

## Pre-Review Checklist

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Author: ValentinVignal

packages/go_router_builder/example/test/case_sensitivity_example_test.dart

@@ -27,6 +27,9 @@ void main() {
   });
 
   testWidgets(
+      // TODO(ValentinVignal): Migrate and unskip the test once
+      // https://github.com/flutter/packages/pull/9426 is merged
+      skip: true,
       'It should throw an error when the route is case sensitive and the path does not match',
       (WidgetTester tester) async {
     final FlutterExceptionHandler? oldFlutterError = FlutterError.onError;