chore(deps): bump build_runner from 2.4.6 to 2.4.8

Bumps [build_runner](https://github.com/dart-lang/build) from 2.4.6 to 2.4.8.
- [Release notes](https://github.com/dart-lang/build/releases)
- [Commits](https://github.com/dart-lang/build/compare/build_runner-v2.4.6...build_runner-v2.4.8)

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

Signed-off-by: dependabot[bot] <support@github.com>

pubspec.lock

@@ -221,10 +221,10 @@ packages:
     dependency: "direct dev"
     description:
       name: build_runner
-      sha256: "10c6bcdbf9d049a0b666702cf1cee4ddfdc38f02a19d35ae392863b47519848b"
+      sha256: "581bacf68f89ec8792f5e5a0b2c4decd1c948e97ce659dc783688c8a88fbec21"
       url: "https://pub.dev"
     source: hosted
-    version: "2.4.6"
+    version: "2.4.8"
   build_runner_core:
     dependency: transitive
     description:

pubspec.yaml

@@ -128,7 +128,7 @@ dependencies:
   spotify: ^0.13.3
 
 dev_dependencies:
-  build_runner: ^2.3.2
+  build_runner: ^2.4.8
   envied_generator: ^0.3.0+3
   flutter_distributor: ^0.0.2
   flutter_gen_runner: ^5.1.0+1