Bump build_runner from 2.4.13 to 2.4.15 in /auto_submit

Bumps [build_runner](https://github.com/dart-lang/build) from 2.4.13 to 2.4.15.
- [Release notes](https://github.com/dart-lang/build/releases)
- [Commits](dart-lang/build@build_runner-v2.4.13...build_runner-v2.4.15)

---
updated-dependencies:
- dependency-name: build_runner
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

auto_submit/pubspec.yaml

@@ -33,7 +33,7 @@ dependencies:
   yaml: 3.1.2
 
 dev_dependencies:
-  build_runner: 2.4.13
+  build_runner: 2.4.15
   dart_flutter_team_lints: 3.4.0
   json_serializable: 6.9.0
   mockito: 5.4.4