Update puffin_viewer requirement from 0.6 to 0.8

Updates the requirements on [puffin_viewer](https://github.com/EmbarkStudios/puffin) to permit the latest version.
- [Release notes](https://github.com/EmbarkStudios/puffin/releases)
- [Changelog](https://github.com/EmbarkStudios/puffin/blob/main/CHANGELOG.md)
- [Commits](https://github.com/EmbarkStudios/puffin/compare/0.6.0...puffin_viewer-0.8.0)

---
updated-dependencies:
- dependency-name: puffin_viewer
  dependency-type: direct:production
...

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

game/Cargo.toml

@@ -36,7 +36,7 @@ async-trait = "0.1.51"
 webbrowser = "0.5"
 
 [dev-dependencies]
-puffin_viewer = "0.6"
+puffin_viewer = "0.8"
 
 [build-dependencies]
 vergen = "5"