doc: replace pub run with dart run (#9629)

packages/devtools_app/test/test_infra/scenes/README.md

diff --git a/packages/devtools_app/test/test_infra/scenes/README.md b/packages/devtools_app/test/test_infra/scenes/README.md
index 87a3523..c880ece 100644
--- a/packages/devtools_app/test/test_infra/scenes/README.md
+++ b/packages/devtools_app/test/test_infra/scenes/README.md
@@ -8,7 +8,7 @@
 
 To generate scene runners:
 ```
-flutter pub run build_runner build --delete-conflicting-outputs
+dart run build_runner build --delete-conflicting-outputs
 ```
 
 To run: