Bump flutter_lints from 4.0.0 to 6.0.0 in /cached_network_image_web

Bumps [flutter_lints](https://github.com/flutter/packages/tree/main/packages) from 4.0.0 to 6.0.0.
- [Commits](https://github.com/flutter/packages/commits/flutter_lints-v6.0.0/packages)

---
updated-dependencies:
- dependency-name: flutter_lints
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

cached_network_image_web/pubspec.yaml

@@ -17,6 +17,6 @@ dependencies:
   material_ui: ^1.0.0
 dev_dependencies:
   file: '>=7.0.0 <8.0.0'
-  flutter_lints: ^4.0.0
+  flutter_lints: ">=4.0.0 <7.0.0"
   flutter_test:
     sdk: flutter