Bump dartdoc from 7.0.2 to 8.0.2 (#2146)

Bumps [dartdoc](https://github.com/dart-lang/dartdoc) from 7.0.2 to 8.0.2.
- [Release notes](https://github.com/dart-lang/dartdoc/releases)
- [Changelog](https://github.com/dart-lang/dartdoc/blob/main/CHANGELOG.md)
- [Commits](dart-lang/dartdoc@v7.0.2...v8.0.2)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pubspec.yaml

@@ -42,7 +42,7 @@ dev_dependencies:
   archive: ^3.1.2
   crypto: ^3.0.0
   dart_style: ^2.0.0
-  dartdoc: ">=6.0.0 <8.0.0"
+  dartdoc: ">=6.0.0 <9.0.0"
   grinder: ^0.9.0
   node_preamble: ^2.0.2
   lints: ">=2.0.0 <4.0.0"