Bump build_runner from 2.4.8 to 2.4.9

Bumps [build_runner](https://github.com/dart-lang/build) from 2.4.8 to 2.4.9.
- [Release notes](https://github.com/dart-lang/build/releases)
- [Commits](dart-lang/build@build_runner-v2.4.8...build_runner-v2.4.9)

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

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

pubspec.lock

@@ -77,10 +77,10 @@ packages:
     dependency: "direct dev"
     description:
       name: build_runner
-      sha256: "581bacf68f89ec8792f5e5a0b2c4decd1c948e97ce659dc783688c8a88fbec21"
+      sha256: "3ac61a79bfb6f6cc11f693591063a7f19a7af628dc52f141743edac5c16e8c22"
       url: "https://pub.dev"
     source: hosted
-    version: "2.4.8"
+    version: "2.4.9"
   build_runner_core:
     dependency: transitive
     description: