Bump flutter_lints in /web_embedding/element_embedding_demo

Bumps [flutter_lints](https://github.com/flutter/packages/tree/main/packages) from 4.0.0 to 5.0.0.
- [Release notes](https://github.com/flutter/packages/releases)
- [Commits](https://github.com/flutter/packages/commits/flutter_lints-v5.0.0/packages)

---
updated-dependencies:
- dependency-name: flutter_lints
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

web_embedding/element_embedding_demo/pubspec.yaml

@@ -13,7 +13,7 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
-  flutter_lints: ^4.0.0
+  flutter_lints: ^5.0.0
 
 flutter:
   uses-material-design: true