Fix syntax error in docstring (#128692)

diff --git a/packages/flutter_test/lib/src/matchers.dart b/packages/flutter_test/lib/src/matchers.dart
index ed93e71..0c287d1 100644
--- a/packages/flutter_test/lib/src/matchers.dart
+++ b/packages/flutter_test/lib/src/matchers.dart
@@ -436,7 +436,7 @@
 ///   });
 ///
 ///   await testMain();
-/// });
+/// }
 /// ```
 /// {@end-tool}
 /// {@endtemplate}