chore(deps): bump retrofit_generator from 7.0.8 to 8.0.3

Bumps [retrofit_generator](https://github.com/trevorwang/retrofit.dart) from 7.0.8 to 8.0.3.
- [Release notes](https://github.com/trevorwang/retrofit.dart/releases)
- [Commits](trevorwang/retrofit.dart@7.0.8...8.0.3)

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

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

pubspec.yaml

@@ -16,6 +16,6 @@ dependencies:
 dev_dependencies:
   build_runner: ^2.1.2
   json_serializable: ^6.2.0
-  retrofit_generator: ^7.0.1
+  retrofit_generator: ">=7.0.1 <9.0.0"
   test: ^1.6.0
   very_good_analysis: ^5.0.0+1