[dart-dio] Fix the version of the sample dependencies

Author: fa0311

samples/openapi3/client/petstore/dart-dio/petstore_client_lib_fake_tests/pubspec.yaml

@@ -10,7 +10,7 @@ environment:
 dev_dependencies:
   built_collection: 5.1.1
   built_value: 8.4.3
-  dio: 5.2.1
+  dio: 5.7.0
   http_mock_adapter: 0.4.2
   mockito: 5.2.0
   openapi: