Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: buenaflor

packages/flutter/test/user_interaction/sentry_user_interaction_widget_test.dart

@@ -658,7 +658,7 @@ void main() {
         expect(firstSpan, isA<IdleRecordingSentrySpanV2>());
 
         // Simulate descendant activity by starting a child span
-        fixture.hub.startSpanSync('child-work', (span) {});
+        fixture.hub.startSpanSync('child-work', (_) {});
 
         await Future<void>.delayed(Duration.zero);
         // Tap a different widget