downgrade build runner

Author: Dario-Maselli

pubspec.yaml

@@ -25,7 +25,7 @@ dependencies:
   url_launcher: ^6.1.8
 
 dev_dependencies:
-  build_runner: ^2.4.15
+  build_runner: ^2.4.9
   fake_async: ^1.3.1
   flutter_test: { sdk: flutter }
   mockito: ^5.4.4